Frozen Period Research Articles

Land Application of Sugar Beet By‐products: Effects on Runoff and Percolating Water Quality

Water quality concerns, including greater potential for nutrient transport to surface waters resulting in eutrophication and nutrient leaching to ground water, exist when agricultural or food processing industry wastes and by-products are land applied. Plot- and field-scale studies were conducted to evaluate the effects of sugar beet by-products on NO3-N and P losses and biochemical oxygen demand (BOD) in runoff and NO3-N concentrations in percolating waters. In the runoff plot study, treatments in the first year included two rates (224 and 448 Mg ha(-1) fresh weight) of pulp and spoiled beets and a nonfertilized control. In the second year, no by-products were applied on the treated plots, the control treatment was fertilized with N fertilizer, and an additional treatment was added as a nonfertilized control in buffer areas. Wheat (Triticum aestivum L.) was grown in the year of by-product application and sugar beet (Beta vulgaris L.) in the following year. In the percolation field study, the treatments were the control, pulp (224 Mg ha(-)(1)), and spoiled beets (224 Mg ha(-1)). Results from the runoff plot showed that both by-products caused immobilization of soil inorganic N and thus reduced NO3-N losses in runoff and soil waters during the first growing season. There was some risk of NO3-N exceeding the drinking water limit of 10 mg L(-1), especially between the period of wheat harvest and soil freezing in fall when pulp was applied at 448 Mg ha(-1). The field-scale study showed that by-product application at 224 Mg ha(-1) did not result in increased ground water NO3-N concentrations. Application of spoiled beets at both rates caused significantly higher BODs in runoff in the first year of application. The concentrations of total and soluble reactive P (SRP) were also higher from both rates of spoiled beet application and from the higher application rate of pulp during the 2-yr study period. These high BODs and total P and SRP concentrations in runoff waters from land application of sugar beet by-product suggest that application rates should not be higher than 224 Mg ha(-1). Best management practices that prevent runoff from entering surface waters directly from these fields are warranted.

Using Different Methods to Tenderize Spent Hens Meat

The aim of this study is tenderizing spent hens meat by using cheap local materials such as bitter orange juice, vinegar, salt and sugar for 1,2, 3 and 4h, distill water is used (T ) in curing to make it a s 1 standard. Bitter orange juice (acidity of 1.5) (T ), vinegar (acidity of 7) (T ), table salt (2%) (T ) and sugar (2%) 2 3 4 (T ) were used. The processed meat was storied under -18 C ± 2 C for a month to investigate the influence 5 o o of the type of treatment and the periods of storing and submersion on the sensory properties and chemical qualities through estimating the percentage of moisture, hydrogen number pH, volume of the released extract. A sensory properties evaluation of the qualities of flavor, juiciness, tenderness and overall acceptance was carried out. Results of curing in the different solutions revealed a decreased pH value in (T ) 2 and T ; while the highest significant differences (p<0.05) was in samples T. Besides, there were no 3 4 significant differences concerning the periods of curing. As far as the period of freezing is concerned, a significant increase in pH of the samples was noticed, T had the upper degree. There were no significant 4 differences concerning the periods of curing. The percentage of moisture increased significantly (p<0.05) of the treatment groups compared with T. The highest significant differences (p<0.05) were found in T. A 1 4 significant (p<0.05) increase occurred in the percentage of moisture when it was frozen and cured. Besides, there were significant differences (p<0.05) concerning the period of curing. A decrease was noticed of the volume of the released extract. The highest significant (p<0.05) difference was in T and the lowest one was 1 in T. It was also noticed that significant (p<0.05) increase of the frozen sample, the highest significant 4 difference (p<0.05) was in T and the lowest one was in T. Results of sensory evaluation indicated the 1 4 improvement of the sensory qualities of the samples treated with the different solutions especially of tenderness and juiciness. These results were reflected on the quality of general acceptance by th e consumer of the samples. Results of sensory evaluation revealed that T and T was the best sample. 2 4 Significant differences (p<0.05) as far as the periods of curing were noticed. Thus we can recommend using 2% salt and bitter orange juice (1.5 acidity) in curing spent hens meat.

Response of soil heat-water processes to vegetation cover on the typical permafrost and seasonally frozen soil in the headwaters of the Yangtze and Yellow Rivers

The response of soil temperature and moisture to vegetative cover in the active layer of permafrost and seasonally frozen soil were assessed and compared. Soil temperature and moisture, under a range of vegetation covers (92%, 65% and 30%) in the permafrost and vegetation covers (95%, 70%-80%, 40%-50% and 10%) in the seasonally frozen soil, were measured on a daily basis. A decline in vegetation cover led to a decrease in the integral of freezing depth of active permafrost layer, but an increase in seasonally frozen soil. The maximum invasion depth and duration of the negative isotherm during the frozen period and of the positive isotherm during the non-frozen period clearly increased when vegetation cover declined. With a reduction of vegetation cover, the soil moisture in the active layer of the permafrost decreased for depths of 0.20-0.60 m, but increased for depths of 0.60-0.80 m, while for seasonally frozen soil, soil moisture of the entire profile (0.10-1.20 m) increased. Variation in vegetation cover alters soil heat-water processes, but the response to it is different between permafrost and seasonally frozen soil.

Repeated freeze–thaw cycles changed organic matter quality in a temperate forest soil

AbstractUnder temperate climate, the frequency of extreme weather events such as intensive freezing or frequent thawing periods during winter might increase in the future. It was shown that frost and subsequent thawing may affect the fluxes of C and N in soils. In a laboratory study, we investigated the effect of frost intensity and repeated freeze–thaw cycles on the quality and quantity of soil organic matter (SOM) in a Haplic Podzol from a Norway spruce forest. Undisturbed soil columns comprising O layer and top mineral soil were treated as followed: control (+5°C), frost at –3°C, –8°C, and –13°C. After a 2‐week freezing period, frozen soils were thawed at +5°C and irrigated with 80 mm water at a rate of 4 mm d–1. Lignin contents were not significantly affected by repeated freeze–thaw cycles. Phospholipid fatty acid (PLFA) contents decreased in the mineral soil, and PLFA patterns indicate that fungi are more susceptible to soil frost than bacteria. Amounts of both plant and microbial sugars generally decreased with increasing frost intensity. These changes cannot be explained by increased mineralization of sugars or by leaching with DOM nor by a decreased microbial activity and, thus, sugar production with increasing frost intensity. Also physical stabilization of sugars due to frost‐induced changes in soil structure can be ruled out as sugar extraction was carried out on ground bulk soil. Therefore, the only possible explanation for the disappearance of plant and microbial sugars upon soil freezing are chemical alterations of sugar molecules leading to SOM stabilization.

The effects of prolonged deep freezing on the biomechanical properties of osteochondral allografts

Musculo-skeletal allografts sterilized and deep frozen are among the most common human tissue to be preserved and utilized in modern medicine. The effects of a long deep freezing period on cortical bone has already been evaluated and found to be insignificant. However, there are no reports about the influences of a protracted deep freezing period on osteochondral allografts. One hundred osteochondral cylinders were taken from a fresh specimen and humeral heads of 1 year, 2 years, 3 years and 4 year old bones. Twenty chips from each period, with a minimum of 3 chips per humeral head. Each was mechanically tested by 3 point compression. The fresh osteochondral allografts were significantly mechanically better than the deep frozen osteochondral allografts. There was no statistical significant time dependent difference between the deep frozen groups in relation to the freezing period. Therefore, we conclude that, from the mechanical point of view deep freezing of osteochondral allografts over a period of 4 years, is safe without further deterioration of the biomechanical properties of the osteochondral allografts.

Survival and recovery of Phaeocystis antarctica (Prymnesiophyceae) from prolonged darkness and freezing

The colony-forming haptophyte Phaeocystis antarctica is an important primary producer in the Ross Sea, and must survive long periods of darkness and freezing temperature in this extreme environment. We conducted experiments on the responses of P. antarctica-dominated phytoplankton assemblages to prolonged periods of darkness and freezing. Chlorophyll and photosynthetic capacity of the alga declined nonlinearly and independently of each other in the dark, and darkness alone would potentially reduce photosynthetic capacity by only 60 per cent over 150 days (approximately the length of the Antarctic winter in the southern Ross Sea). The estimated reduction of colonial mucous carbon is higher than that of colonial cell carbon, suggesting metabolism of the colonial matrix in the dark. The alga quickly resumed growth upon return to light. Phaeocystis antarctica also survived freezing, although longer freezing durations lengthened the lag before growth resumption. Particulate dimethylsulfoniopropionate relative to chlorophyll increased upon freezing and decreased upon darkness. Taken together, the abilities of P. antarctica to survive freezing and initiate growth quickly after darkness may provide it with the capability to survive in both the ice and the water column, and help explain its repeated dominance in austral spring blooms in the Ross Sea and elsewhere in the Southern Ocean.

High tolerance to repeated cycles of freezing and thawing in different Trichinella nativa isolates

Trichinella nativa is the most frequent Trichinella species in arctic wildlife and also the predominating species seen in Norwegian fauna. The adaptation of T. nativa to a cold climate is reflected by the well-documented freeze tolerance of its muscle larvae. The ability of the larvae to survive repeated freezing and thawing events has not however been elucidated and was investigated in the present study, using an Alaskan isolate and two isolates from coastal and inland Norway, respectively. Each T. nativa isolate was inoculated in foxes (Vulpes vulpes) and the muscle tissue obtained after 20 weeks was minced and divided into freezer bags. In the initial part of the study, the bags were exposed to either continuous freezing (-5 degrees C) for up to 7 weeks or freezing (-5 degrees C) for up to 7 weeks with seven overnight (+21 degrees C) thawing events. Once a week a bag was removed from each group, the meat was digested and muscle larvae isolated. In vitro assessment of larval viability was carried out based on larval motility (active vs non-active) and morphology, coiled (alive) or C-shaped (dead). Larval infectivity was subsequently bioassayed in mice, administering 500 larvae per mouse. The mice were euthanised 4 weeks post inoculation, the muscle digested and larvae per gram (lpg) and reproductive capacity index (RCI) were calculated. During the second part of the study, some of the minced fox muscle, exposed to the initial freeze protocol, was stored for a further 23 weeks at -18 degrees C prior to in vitro and in vivo assessment of larval viability and infectivity. The study demonstrated that Trichinella isolates originating from carnivores from higher northern latitudes expressed highest tolerance to freezing and that temperature fluctuations around freezing point, for up to 7 weeks, had little effect on larval infectivity. A negative effect of the initial repeated freeze-thaw events could be demonstrated once the larvae were exposed to longer periods of subsequent deep freezing. Furthermore, it was demonstrated that larval morphology and motility are not suitable for the assessment of infectivity of Trichinella larvae. It was concluded that bioassay in mice was the only suitable method currently available for assessing larval viability.

Effect of storage and freezing on unbound bilirubin measurement

Background Unbound bilirubin ( B f) is a better predictor of bilirubin toxicity than total serum bilirubin (TSB) in the postnatal period. The Food and Drug Administration approved peroxidase test for B f analysis is not currently available in clinical laboratories. The samples are often stored at varying temperature and for varying duration before B f analysis. Methods We evaluated the effect of storing blood samples up to 1 month at − 20 °C and − 80 °C on B f measurement. In a subset of samples collected for neonates enrolled in a prospective B f study, TSB (µmol/l) and B f (μmol/l) were measured by the peroxidase test and then the samples were immediately frozen at − 20 °C ( n = 10) or − 80 °C ( n = 10) for either 2 weeks or at − 20 °C ( n = 16) or − 80 °C ( n = 10) for 1 month. After the designated freezing period, the samples were thawed and TSB and B f measured again. Results There was no effect of storage for 2 weeks at either − 20 °C or − 80 °C on B f measurement. There appears to be no effect on B f after storage at − 80 °C for a month. However, there was significant decrease in B f after storage at − 20 °C for a month. Conclusions The results of this study suggest that blood samples for B f measurement should be analyzed within 2 weeks after collection and storage at − 20 °C.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Long term trend of chemical oxygen demand in Saroma-ko Lagoon, Japan; possible effects of climatic warming

A trend of shortening duration of ice coverage has been reported in many rivers, ponds and lakes around the world due to climatic warming. The shortening will have much influence on organic production due to the greater supply of light intensity and hence on water quality. Chemical Oxygen Demand (COD), a useful measure of water quality, has been monitored over the past thirty years in Saroma-ko Lagoon, a boreal lake in Japan characterized by wintertime ice coverage. Here the data set of water quality in the lagoon is analyzed to reveal long-term trends in COD and the influence of climatic warming on such trends. There has been a significant increasing trend, caused primarily by an abrupt increase in the early 1990s. However, the increase could not be explained by the increased load of organic matter on the lagoon from the river basin and organic production in the lagoon. On the other hand, periods of freezing of the entire surface have tended to be shorter with inevitable thinning of ice over the past forty years, probably due to climatic warming. Ice and planktonic algae are exposed to the low light intensity in situ, which is not optimum for the algal production of organic matter. The shortening and thinning should thus bring an improvement in ambient light conditions for algae, resulting in an increase of organic matter in winter. Most of the organic matter possibly remains even after spring because of the low water temperature. It is highly possible that climatic warming promotes deterioration in water quality in ice-covered lakes.

Long term trend of chemical oxygen demand in Saroma-ko Lagoon, Japan; possible effects of climatic warming

AbstractA trend of shortening duration of ice coverage has been reported in many rivers, ponds and lakes around the world due to climatic warming. The shortening will have much influence on organic production due to the greater supply of light intensity and hence on water quality. Chemical Oxygen Demand (COD), a useful measure of water quality, has been monitored over the past thirty years in Saroma-ko Lagoon, a boreal lake in Japan characterized by wintertime ice coverage. Here the data set of water quality in the lagoon is analyzed to reveal long-term trends in COD and the influence of climatic warming on such trends. There has been a significant increasing trend, caused primarily by an abrupt increase in the early 1990s. However, the increase could not be explained by the increased load of organic matter on the lagoon from the river basin and organic production in the lagoon. On the other hand, periods of freezing of the entire surface have tended to be shorter with inevitable thinning of ice over the past forty years, probably due to climatic warming. Ice and planktonic algae are exposed to the low light intensity in situ, which is not optimum for the algal production of organic matter. The shortening and thinning should thus bring an improvement in ambient light conditions for algae, resulting in an increase of organic matter in winter. Most of the organic matter possibly remains even after spring because of the low water temperature. It is highly possible that climatic warming promotes deterioration in water quality in ice-covered lakes.

Constitutional Limitations on the Ability of States to Rehabilitate Their Failed Electric Utility Restructuring Plans

This Article will review the constitutional limitations that come into play when a state seeks to rehabilitate its failed electric utility restructuring plan. Under the Constitution, utilities are entitled to earn a reasonable return on the assets devoted to public service. A situation in which retail rates are frozen may result in denial of a compensatory return if the electric utility is incurring higher costs to generate or procure its power supply. This is the traditional takings argument based on the Fifth Amendment to the Constitution, as applied to the states under the Fourteenth Amendment. Apart from this commonly asserted argument, however, a different constitutional issue arises in the context of proposed rate freezes. As a matter of procedural due process, a regulated utility cannot be deprived of its opportunity to demonstrate a need for rate relief to achieve the level of profitability that satisfies constitutional requirements. These procedural due process rights are imperiled when, for example, a state simply extends a rate freeze period and thereby denies the electric utility a hearing in which the utility would have an opportunity to make its case for higher rates.

Synergistic effect of vegetation and air temperature changes on soil water content in alpine frost meadow soil in the permafrost region of Qinghai‐Tibet

AbstractSeasonal changes over 2 years (2004–2006) in soil moisture content (θv) of frozen alpine frost meadow soils of the Qinghai‐Tibet plateau permafrost region under three different levels of vegetation cover were investigated. Vegetation cover and air temperature changes had significant effects (synergistic effect) on θv and its distribution in the soil profile. During periods of soil freezing or thawing, the less the vegetation cover, the quicker the temperature drop or rise of soil water, and the shorter the duration of the soil water freeze–thaw response in the active soil layer. Under 30% and 65% vegetation cover the amplitude of variation in θv during the freezing period was 20–26% greater than that under 93% cover, while during the thawing period, it was 1·5‐ to 40·5‐fold greater. The freezing temperature of the surface soil layer, fTs, was 1·6 °C lower under 30% vegetation cover than under 93% vegetation cover. Changes in vegetation cover of the alpine frost meadow affected θv and its distribution, as well as the relationship between θv and soil temperature (Ts). As vegetation cover decreased, soil water circulation in the active layer increased, and the response to temperature of the water distribution across the soil profile was heightened. The quantity of transitional soil phase water at different depths significantly increased as vegetation cover decreased. The influence of vegetation cover and soil temperature distribution led to a relatively dry soil layer in the middle of the profile (0·70–0·80 m) under high vegetation cover. Alpine meadow θv and its pattern of distribution in the permafrost region were the result of the synergistic effect of air temperature and vegetation cover. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Emission of CO 2, CH 4 and N 2O from freshwater marsh in northeast of China

The wetlands play an important role in carbon storage, especially at high latitudes, at which they store nearly one-third of global soil carbons. However, few studies have investigated the emissions of CO 2, CH 4 and N 2O in the long-term, especially effects of freeze–thaw cycles on these gases emissions in freshwater marsh ecosystems. In this paper, we collected greenhouse gas emission data from a freshwater marsh area in China for 4 years, evaluated their release variables and speculated on their potential atmospheric impact. For this paper, we report on the CO 2, CH 4 and N 2O emission rates recorded from June 2002 to November 2005 in the Sanjiang Plain of northeast China. We measured their interannual variations and fluctuations, as well as factors affecting their emissions, and estimated their regulation and freeze–thaw cycle impacts. Our results revealed obvious CO 2 and CH 4 emission fluctuations during the winter months, and during the freeze–thaw cycle, and a strong interannual variation during the growing season. Overall, we documented a close relationship between the CO 2 and CH 4 emissions, implicating some regulatory commonality. We determined that the marsh was a N 2O sink during the winter, but a significant source of N 2O during the freeze–thaw cycle as the temperature increased, especially in early summer. During the thaw–freeze period, the N 2O levels were positively correlated with the water depth. Additionally, water depth greatly governed the interannual variation of the N 2O emissions from the marshes during the thaw–freeze period.

Daily Stream Flow Prediction Capability of Artificial Neural Networks as influenced by Minimum Air Temperature Data

The minimum air temperature influence on training of artificial neural networks (ANNs) for daily stream flow prediction is investigated. For improved computed performances, efficiencies of the conjugate gradient (CG) and Levenberg–Marquardt (L–M) training algorithms are compared. The minimum air temperature influence is studied for a watershed in southern Iran, representing a continuous flow regime with peak flows occurring as a result of individual rainfall events. Peak flow occurrence generally coincides with freezing or near-freezing periods. Based on the results, the L–M algorithm is more efficient than the CG algorithm, so it is used to train four ANNs models for stream flow prediction at time step t+1 from time step t input. Model 1 uses enabled stream flow data as input dimension, Model 2 uses enabled stream flow and single raingauge, Model 3 uses enabled raingauge network and Model 4 uses enabled raingauge network data and minimum air temperature. Validation stage root mean square error (RMSE), root mean absolute error (RMAE) and efficiency (EF) measures are: 25·456, 0·220, 0·580 (Model 1); 17·401, 0·139, 0·813 (Model 2); 12·220, 0·112, 0·916 (Model 3) and 10·383, 0·069, 0·939 (Model 4), respectively. The influence of minimum air temperature on improved Model 4 performance is discussed.

Melt Detection in Antarctic Ice Shelves Using Scatterometers and Microwave Radiometers

Ku-band dual-polarization radar backscatter measurements from the SeaWinds-on-QuikSCAT scatterometer are used to determine periods of surface freeze and melt in the Antarctic ice shelves. The normalized horizontal-polarization radar backscatter (sigmao) and backscatter polarization ratio are used in maximum-likelihood estimation of the ice state. This method is used to infer the daily ice-surface conditions for 25 study locations located on the Ronne, Ross, Larsen, Amery, Shackleton, and other ice shelves. The temporal and spatial variations of the radar response are observed for various neighborhood sizes surrounding each given location during the study period. Criteria for determining the dates of melt onset and freeze-up for each Austral summer are presented. Validation of the ice-state and melt-onset date estimates is performed by analyzing the corresponding brightness temperature (Tb) measurements from Special Sensor Microwave/Imager (SSM/I) radiometers. QuikSCAT sigmao measurements from 1999 to 2003 are analyzed and found to be effective in determining periods of melt in Antarctic ice sheets at high temporal and spatial resolutions. These estimates can be used in studies of the climatic effects of the seasonal and interannual melting of the Antarctic ice sheets

Particle simulation of spontaneous crack generation problems in large‐scale quasi‐static systems

AbstractTo extend the application range of the distinct element method from a laboratory scale into a large scale such as a geological scale, we need to deal with an upscale issue associated with simulating spontaneous crack generation problems in large‐scale quasi‐static systems. Toward this direction, three important simulation issues, which may affect the quality of the particle simulation results of a quasi‐static system, have been addressed in details in this paper. The first simulation issue is how to determine the particle‐scale mechanical properties of a particle from the measured macroscopic mechanical properties of rocks. The second simulation issue is that the fictitious time, rather than the physical time, is used in the particle simulation of a quasi‐static problem. The third simulation issue is that the conventional loading procedure used in the distinct element method is conceptually inaccurate, at least from the force propagation point of view. A new loading procedure is proposed to solve the conceptual problem resulting from the third simulation issue. The proposed loading procedure is comprised of two main types of periods, a loading period and a frozen period. Using the proposed loading procedure, the parameter selection problem stemming from the first issue can be somewhat solved. Since the second issue is an inherent one, it is strongly recommended that a particle‐size sensitivity analysis of at least two different models, which have the same geometry but different smallest particle sizes, be carried out to confirm the particle simulation result of a large‐scale quasi‐static system. The related simulation results have demonstrated the usefulness and correctness of the proposed loading procedure for dealing with spontaneous crack generation problems in large‐scale quasi‐static geological systems. Copyright © 2006 John Wiley &amp; Sons, Ltd.

An efficient clustering scheme for large and dense mobile ad hoc networks (MANETs)

Large and dense MANETs often face scalability problem and need to achieve performance guarantee with the help of a hierarchical structure, typically a cluster control structure. In this paper, an efficient clustering scheme (ECS) is proposed for large and dense MANETs. Mechanisms for cluster formation and cluster maintenance are described and studied in detail. ECS can eliminate the frozen period requirement for cluster formation, reduce cluster overlapping and prolongs the cluster lifetime without producing excessive clustering overheads. The performance of ECS is compared with random competition-based clustering (RCC) and a modified version of highest connectivity clustering (HCC) in terms of clustering overheads, clusterhead lifetime, cluster number and cluster size. Simulation results show that ECS successfully achieves its targets at reducing the cluster overlapping, maintaining a stable cluster structure as well as producing moderate clustering overheads.

CO 2 and N 2O emissions from gleyic soils in the Russian tundra and a German forest during freeze–thaw periods—a microcosm study

Knowledge is scarce on mineralization of soil organic carbon (SOC) in and N 2O emissions from tundra soils in periods of alternate freezing and thawing. Our objectives were to study the CO 2 and N 2O emissions from two silty gleyic soils formed in different climate zones (a gleyic Cryosol located in the Russian tundra, and a stagnic Gleysol located in an oak stand in central Germany) during freeze–thaw events. Soils were adjusted to a matric potential of −0.2 kPa and emissions were measured in 3-h intervals during an incubation period of 50 days including three freeze–thaw cycles. CO 2 emissions from the German oak forest soil were twofold higher than those of the tundra soil. The ratios of the mean CO 2 production rate before the freezing to the mean CO 2 production rate after thawing ranged from 0.63 to 0.73 for the forest soil and from 0.85 to 0.89 for the tundra soil. The specific CO 2-C production rate (CO 2-C/SOC) was 0.16 for the tundra soil and 0.57 for the forest soil. The results indicate that bioavailability of SOC was markedly smaller in the tundra soil than in the forest soil. Large N 2O emissions were found for the German forest soil, but no N 2O emissions were observed for the tundra soil. The main reason for the absence of N 2O emissions was most likely the negligible availability of nitrate for denitrification. There was some indication that the initial increase in mineralization of SOC induced by freezing and thawing differs between soils from various climatic regions, probably mainly due to a differing bioavailability of the SOC and differing releases of nutrients after thawing.

Effects of Food Storage and Handling on Blow Fly (Lucilia sericata) Eggs and Larvae

Flies can cause food-borne disease by transmitting pathogenic microorganisms into the food we eat or by being ingested themselves (“intestinal myiasis”), usually as eggs or larvae contaminating our food. Because eggs and larvae can easily contaminate our food during harvesting, handling, and preparation, this series of experiments was undertaken to define the food preparation conditions that would be necessary to kill contaminating blow fly eggs and larvae. Replicate samples of Lucilia (=Phaenicia) sericata (Meigen) eggs and larvae were exposed to increasing periods of freezing, refrigeration, baking, boiling, frying, and microwaving. Survivors were counted every 6 to 48 h thereafter, and the exposures that were lethal to 50% (LE50), 90% (LE90), and 99% of our samples (LE99) were calculated. All of the tested food-preparation methods killed most or all of the eggs and larvae when exposed for durations typically associated with food preparation. These results indicate that the common methods of food preparation should adequately kill all L. sericata eggs and larvae that may be associated with raw meat. Freezing and extended refrigeration also killed all eggs and larvae. This supports the belief, hitherto unproven, that contamination of cooked meat products most likely occurs at or after the point of retail-consumer contact.