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• 41. [Article] Mid-Latitude (30°–60° N) climatic warming inferred by combining borehole temperatures with surface air temperatures

  copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Mid-Latitude (30°–60° N) climatic warming inferred by combining borehole temperatures with surface air temperatures Author: Harris, Robert N., Chapman, David S. copyrighted by American Geophysical Union Title: Mid-Latitude (30°–60° N) climatic warming inferred by combining borehole temperatures with surface air temperatures Author: Harris, Robert N., Chapman, David S. copyrighted by American Geophysical Union Close

• 42. [Article] Climate change in India inferred from geothermal observations

  copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Climate change in India inferred from geothermal observations Author: Harris, Robert N., Rao, R. U. M., Roy, Sukanta, Chapman, David S. copyrighted by American Geophysical Union Title: Climate change in India inferred from geothermal observations Author: Harris, Robert N., Rao, R. U. M., Roy, Sukanta, Chapman, David S. copyrighted by American Geophysical Union Close

• 43. [Article] Effects of temperature and other abiotic and biotic factors on development and survival of the immature stages of the alfalfa leafcutting bee, Megachile pacifica (Panzer) (=rotundata (F.)) (Hymenoptera:Megachilidae)

  Larval mortality of leafcutting bee, Megachile pacifica (Panzer) (= rotundata (F.)), is high, usually exceeding 50%. Parasites and predators are not a limiting factor in the survival of the progeny. The ...

  Citation × Citation Citation Abstract Copy Title: Effects of temperature and other abiotic and biotic factors on development and survival of the immature stages of the alfalfa leafcutting bee, Megachile pacifica (Panzer) (=rotundata (F.)) (Hymenoptera:Megachilidae) Author: Undurraga O., Jaime M. Larval mortality of leafcutting bee, Megachile pacifica (Panzer) (= rotundata (F.)), is high, usually exceeding 50%. Parasites and predators are not a limiting factor in the survival of the progeny. The disease chalk brood has been an important mortality factor since 1974. Inadequate food supply, pollen and nectar, may affect the survival of the progeny. Genetic differences within and between populations and the saponin content of alfalfa leaves do not affect brood production or survival. Domicile design and protection may also have a great influence on survival. Temperatures exceeding 50°C occur in cells when nesting material receives direct sunlight or when nesting material is housed in domiciles with poor ventilation and insulation. There are temperature differences between cells in a series, between nest positions within a domicile, and between types of nesting materials. There is no direct relationship between ambient and cell temperatures because the latter are influenced by exposure, nesting media, placement, and domicile structure. High internal bee body temperatures may occur during most bee activities, excluding resting. The effects of high temperatures on the adult bee or the eggs she contains are not known. Although larval development can proceed at temperatures below 21°C, survival is reduced. Adult activity, like metabolic larval development, can be conditioned to unusually high or low temperatures; thus, there is no absolute temperature threshold for development or activity in this bee. Eggs and young larvae reared at a constant 30°C had over 85% survival, in most years. An ambient temperature of 45°C applied for one to three hours resulted in a higher mortality of eggs and early instars than the control temperature of 30°C; at 50°C, mortality was complete. Exceptions were obtained for either situation. Half hour exposure at 50°C ambient temperature was also detrimental to immatures. An ambient temperature of 40°C in general does not affect survival of immatures. In-cell temperatures were at least 5°C lower than ambient temperatures in incubators during treatments. Repeating heat treatments on two or more days was not as severe as the duration of treatments. Larvae showed heat tolerance when exposed to two to three hours at 45°C but not to one hour, but some exceptions occurred. The mechanism for heat tolerance is not well understood, and may be related to a conditioning of individuals to high temperatures. A seasonal effect on survival was obtained and appears not to be related to the age of the laying females, nor to the generations, but rather to the thermal history to which the immatures were exposed. Heat susceptibility of eggs and early instars seemed to be similar. Fourth and fifth instars were the most heat tolerant of all larval stages. Exposure of young larvae to low temperatures before they were exposed to high temperatures did not increase mortality. However, sublethal high temperatures were generally less harmful to the immatures that were conditioned but this acclimation of the larvae did not occur in every test. Upper threshold temperature limits cannot be precisely defined, nevertheless, cell temperatures over 40°C result in egg and larval mortality. Brief exposure to 45°C was the upper limit that developing pupae could tolerate; 50°C was lethal. Pupae were most heat sensitive between three and six days before emergence. When exposed to high temperatures, pupae and emerging adults were able to arrest development. Pupae and emerging adults can be conditioned to tolerate short exposures to lethal temperatures up to seven days before emergence. Low temperatures did not affect the survival of pupae. Development of pupae and emerging adults could be arrested for up to a week at 15.6°C without harmful effect. Development and emergence proceed at 21 °C, but pupae need at least 2.5 hours per day of temperatures above 21°C to survive when not in an arrested state. Pupae not exposed to temperature above 29°C during 24 hours, emerged normally. Incubation at 29.5°C for less than 10 hours per day delayed the emergence. Pupae maintained at 15.6 °C for 22 hours per day for 8 days or for 20 hours per day for 16 days emerged after a delay longer than the period of cold. Cooling the emerging bees after high temperature treatment appeared to be more detrimental than cooling before exposures to high temperatures. The detrimental effect of extreme temperatures was shown on the survival of eggs, young larvae, and pupae, but possible chronic effects on later stadia were not studied. Title: Effects of temperature and other abiotic and biotic factors on development and survival of the immature stages of the alfalfa leafcutting bee, Megachile pacifica (Panzer) (=rotundata (F.)) (Hymenoptera:Megachilidae) Author: Undurraga O., Jaime M. Larval mortality of leafcutting bee, Megachile pacifica (Panzer) (= rotundata (F.)), is high, usually exceeding 50%. Parasites and predators are not a limiting factor in the survival of the progeny. The disease chalk brood has been an important mortality factor since 1974. Inadequate food supply, pollen and nectar, may affect the survival of the progeny. Genetic differences within and between populations and the saponin content of alfalfa leaves do not affect brood production or survival. Domicile design and protection may also have a great influence on survival. Temperatures exceeding 50°C occur in cells when nesting material receives direct sunlight or when nesting material is housed in domiciles with poor ventilation and insulation. There are temperature differences between cells in a series, between nest positions within a domicile, and between types of nesting materials. There is no direct relationship between ambient and cell temperatures because the latter are influenced by exposure, nesting media, placement, and domicile structure. High internal bee body temperatures may occur during most bee activities, excluding resting. The effects of high temperatures on the adult bee or the eggs she contains are not known. Although larval development can proceed at temperatures below 21°C, survival is reduced. Adult activity, like metabolic larval development, can be conditioned to unusually high or low temperatures; thus, there is no absolute temperature threshold for development or activity in this bee. Eggs and young larvae reared at a constant 30°C had over 85% survival, in most years. An ambient temperature of 45°C applied for one to three hours resulted in a higher mortality of eggs and early instars than the control temperature of 30°C; at 50°C, mortality was complete. Exceptions were obtained for either situation. Half hour exposure at 50°C ambient temperature was also detrimental to immatures. An ambient temperature of 40°C in general does not affect survival of immatures. In-cell temperatures were at least 5°C lower than ambient temperatures in incubators during treatments. Repeating heat treatments on two or more days was not as severe as the duration of treatments. Larvae showed heat tolerance when exposed to two to three hours at 45°C but not to one hour, but some exceptions occurred. The mechanism for heat tolerance is not well understood, and may be related to a conditioning of individuals to high temperatures. A seasonal effect on survival was obtained and appears not to be related to the age of the laying females, nor to the generations, but rather to the thermal history to which the immatures were exposed. Heat susceptibility of eggs and early instars seemed to be similar. Fourth and fifth instars were the most heat tolerant of all larval stages. Exposure of young larvae to low temperatures before they were exposed to high temperatures did not increase mortality. However, sublethal high temperatures were generally less harmful to the immatures that were conditioned but this acclimation of the larvae did not occur in every test. Upper threshold temperature limits cannot be precisely defined, nevertheless, cell temperatures over 40°C result in egg and larval mortality. Brief exposure to 45°C was the upper limit that developing pupae could tolerate; 50°C was lethal. Pupae were most heat sensitive between three and six days before emergence. When exposed to high temperatures, pupae and emerging adults were able to arrest development. Pupae and emerging adults can be conditioned to tolerate short exposures to lethal temperatures up to seven days before emergence. Low temperatures did not affect the survival of pupae. Development of pupae and emerging adults could be arrested for up to a week at 15.6°C without harmful effect. Development and emergence proceed at 21 °C, but pupae need at least 2.5 hours per day of temperatures above 21°C to survive when not in an arrested state. Pupae not exposed to temperature above 29°C during 24 hours, emerged normally. Incubation at 29.5°C for less than 10 hours per day delayed the emergence. Pupae maintained at 15.6 °C for 22 hours per day for 8 days or for 20 hours per day for 16 days emerged after a delay longer than the period of cold. Cooling the emerging bees after high temperature treatment appeared to be more detrimental than cooling before exposures to high temperatures. The detrimental effect of extreme temperatures was shown on the survival of eggs, young larvae, and pupae, but possible chronic effects on later stadia were not studied. Close

• 44. [Article] Effect of climate change on water temperature and attainment of water temperature criteria in the Yaquina Estuary, Oregon (USA)

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier ...

  Citation × Citation Citation Abstract Copy Title: Effect of climate change on water temperature and attainment of water temperature criteria in the Yaquina Estuary, Oregon (USA) Author: Sharp, Darrin, Collura, T. Chris Mochon, Brown, Cheryl A. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/estuarine-coastal-and-shelf-science/ Title: Effect of climate change on water temperature and attainment of water temperature criteria in the Yaquina Estuary, Oregon (USA) Author: Sharp, Darrin, Collura, T. Chris Mochon, Brown, Cheryl A. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/estuarine-coastal-and-shelf-science/ Close

• 45. [Article] Processing effects on the ductility of chromium-vanadium alloys

  The next generation of high temperature structural alloys must exhibit exceptional resistance to fracture, creep, oxidation, and fatigue at high temperatures. Chromium is being considered due to its high ...

  Citation × Citation Citation Abstract Copy Title: Processing effects on the ductility of chromium-vanadium alloys Author: Murdock, Hailey M. The next generation of high temperature structural alloys must exhibit exceptional resistance to fracture, creep, oxidation, and fatigue at high temperatures. Chromium is being considered due to its high melting point (>1800°C), relatively low density (~7.2 g/cc), high temperature strength, and oxidation resistance. Limiting the use of chromium is its high ductile-to-brittle transition temperature. Previous efforts to reduce the ductile-to-brittle transition temperature have considered elimination of embrittling interstitals, increasing the grain size, pre-deformation and alloying. Recent computational studies have renewed interest in using alloying additions to ductilize chromium. A series of first principles calculations recently revealed elements (Ti, Zr, Hf, Nb, V) which have potential to reduce the ductile-to-brittle transition temperature when alloyed with chromium. To experimentally measure the effects of alloying and processing on the ductile-to-brittle transition temperature, chromium-vanadium alloy samples of 3 different compositions were prepared and compared to nominally pure chromium. Chromium vanadium samples were prepared from powders, hot isostatically pressed, heat treated at 1300°C and extruded at 1200°C. Elevated temperature Vickers hardness, elevated temperature tensile and elevated 3-point bend tests were performed. A diffusion study was performed using microprobe analysis to assist in the development of homogenization procedures for the alloys. Fracture surface analysis of bend and tensile specimens was used to determine the mode of fracture in bend and tensile specimens. Elevated temperature tensile tests determined a relationship between temperature and ductility in 100%Cr and 25%Cr-75%V alloys. Results from elevated temperature Vickers hardness suggest alloying with vanadium increases the strength by a factor of two. Premature failure in elevated temperature 3-point bend specimens and elevated temperature tensile tests made it difficult to quantify the effect of vanadium in affecting the ductility of chromium. Electron microscopy observations indicate that mechanical damage, likely caused by extrusion, is responsible for initiating the premature failures. Despite this complication, evidence of micro- and macro-scale ductile fracture mechanisms on the fracture surfaces of the Cr-V alloys indicate that the addition of vanadium indeed improves the ductility of chromium. Title: Processing effects on the ductility of chromium-vanadium alloys Author: Murdock, Hailey M. The next generation of high temperature structural alloys must exhibit exceptional resistance to fracture, creep, oxidation, and fatigue at high temperatures. Chromium is being considered due to its high melting point (>1800°C), relatively low density (~7.2 g/cc), high temperature strength, and oxidation resistance. Limiting the use of chromium is its high ductile-to-brittle transition temperature. Previous efforts to reduce the ductile-to-brittle transition temperature have considered elimination of embrittling interstitals, increasing the grain size, pre-deformation and alloying. Recent computational studies have renewed interest in using alloying additions to ductilize chromium. A series of first principles calculations recently revealed elements (Ti, Zr, Hf, Nb, V) which have potential to reduce the ductile-to-brittle transition temperature when alloyed with chromium. To experimentally measure the effects of alloying and processing on the ductile-to-brittle transition temperature, chromium-vanadium alloy samples of 3 different compositions were prepared and compared to nominally pure chromium. Chromium vanadium samples were prepared from powders, hot isostatically pressed, heat treated at 1300°C and extruded at 1200°C. Elevated temperature Vickers hardness, elevated temperature tensile and elevated 3-point bend tests were performed. A diffusion study was performed using microprobe analysis to assist in the development of homogenization procedures for the alloys. Fracture surface analysis of bend and tensile specimens was used to determine the mode of fracture in bend and tensile specimens. Elevated temperature tensile tests determined a relationship between temperature and ductility in 100%Cr and 25%Cr-75%V alloys. Results from elevated temperature Vickers hardness suggest alloying with vanadium increases the strength by a factor of two. Premature failure in elevated temperature 3-point bend specimens and elevated temperature tensile tests made it difficult to quantify the effect of vanadium in affecting the ductility of chromium. Electron microscopy observations indicate that mechanical damage, likely caused by extrusion, is responsible for initiating the premature failures. Despite this complication, evidence of micro- and macro-scale ductile fracture mechanisms on the fracture surfaces of the Cr-V alloys indicate that the addition of vanadium indeed improves the ductility of chromium. Close

• 46. [Article] Interaction and behavior of the redside shiner (Richardsonius balteatus) and the steelhead trout (Salmo gairdneri) in western Oregon : the influence of water temperature

  Water temperature influenced interactions between redside shiners and juvenile steelhead trout (≥1+) in the field and the laboratory. Distribution of the two species within various habitats was determined ...

  Citation × Citation Citation Abstract Copy Title: Interaction and behavior of the redside shiner (Richardsonius balteatus) and the steelhead trout (Salmo gairdneri) in western Oregon : the influence of water temperature Author: Reeves, Gordon H. Water temperature influenced interactions between redside shiners and juvenile steelhead trout (≥1+) in the field and the laboratory. Distribution of the two species within various habitats was determined in three streams with different water temperature regimes. The range of habitats occupied by trout in allopatry at cool temperatures and at intermediate temperatures in sympatry was similar but habitats occupied by shiners in allopatry at warm temperatures and in sympatry at intermediate temperatures differed. Shiners at warm temperatures in allopatry inhabited areas of intermediate depth and high velocity, similar to those inhabited by trout in the other streams. In the presence of trout at intermediate temperatures, shiners were found in deep, slow water. Water temperature and the presence of the other species influenced production, activity, and distribution of both trout and shiners in laboratory streams. Trout dominated at cool temperatures (12-15°C) and shiners prevailed at warm temperatures (19-22°C). The redside shiner exhibited two basic social organizations, loose aggregations and defense of an area. The type of organization observed varied with water temperature, abundance of food, and presence or absence of juvenile steelhead trout. The behavioral repertoire of the redside shiner was diverse. Size of the individual and proprietorship of an area were important in determining outcomes of interactions. Intensity of individual encounters varied with conditions in the laboratory streams. Plasticity of its social behavior appears to contribute to the ecological success of the redside shiner. Title: Interaction and behavior of the redside shiner (Richardsonius balteatus) and the steelhead trout (Salmo gairdneri) in western Oregon : the influence of water temperature Author: Reeves, Gordon H. Water temperature influenced interactions between redside shiners and juvenile steelhead trout (≥1+) in the field and the laboratory. Distribution of the two species within various habitats was determined in three streams with different water temperature regimes. The range of habitats occupied by trout in allopatry at cool temperatures and at intermediate temperatures in sympatry was similar but habitats occupied by shiners in allopatry at warm temperatures and in sympatry at intermediate temperatures differed. Shiners at warm temperatures in allopatry inhabited areas of intermediate depth and high velocity, similar to those inhabited by trout in the other streams. In the presence of trout at intermediate temperatures, shiners were found in deep, slow water. Water temperature and the presence of the other species influenced production, activity, and distribution of both trout and shiners in laboratory streams. Trout dominated at cool temperatures (12-15°C) and shiners prevailed at warm temperatures (19-22°C). The redside shiner exhibited two basic social organizations, loose aggregations and defense of an area. The type of organization observed varied with water temperature, abundance of food, and presence or absence of juvenile steelhead trout. The behavioral repertoire of the redside shiner was diverse. Size of the individual and proprietorship of an area were important in determining outcomes of interactions. Intensity of individual encounters varied with conditions in the laboratory streams. Plasticity of its social behavior appears to contribute to the ecological success of the redside shiner. Close

• 47. [Article] Amplification and dampening of soil respiration by changes in temperature variability

  NEWS COVERAGE: A news release based on this journal publication, which is written for a lay audience and has been approved by an author of the study, is available online: http://bit.ly/lyWhTB

  Citation × Citation Citation Abstract Copy Title: Amplification and dampening of soil respiration by changes in temperature variability Author: Loescher, H. W., Thomann, E., Sierra, C. A., Harmon, M. E., Perakis, S. S. NEWS COVERAGE: A news release based on this journal publication, which is written for a lay audience and has been approved by an author of the study, is available online: http://bit.ly/lyWhTB Title: Amplification and dampening of soil respiration by changes in temperature variability Author: Loescher, H. W., Thomann, E., Sierra, C. A., Harmon, M. E., Perakis, S. S. NEWS COVERAGE: A news release based on this journal publication, which is written for a lay audience and has been approved by an author of the study, is available online: http://bit.ly/lyWhTB Close

• 48. [Article] The effects of elevated temperature and stress on immune function in juvenile chinook salmon (Oncorhynchus tshawytscha)

  Stress, including extreme or rapidly changing temperatures, are known to have deleterious effects on fish health and physiology. This thesis examines the combined effects of elevated acclimation temperature ...

  Citation × Citation Citation Abstract Copy Title: The effects of elevated temperature and stress on immune function in juvenile chinook salmon (Oncorhynchus tshawytscha) Author: Harrahy, Laura Nicole Martini Stress, including extreme or rapidly changing temperatures, are known to have deleterious effects on fish health and physiology. This thesis examines the combined effects of elevated acclimation temperature and acute handling stress on the number of antibody producing cells, plasma lysozyme concentrations, and the number of pronephric leukocytes in juvenile chinook salmon (Oncorhynchus tshawytscha). An additional goal of this thesis was to explore the effects of a temperature fluctuation, as a potential instigator of thermal shock, on innate immunity in wild fall chinook salmon of the Columbia River, specifically to determine if there are effects on plasma lysozyme concentrations and on the frequencies of lymphocytes, neutrophils, and thrombocytes in circulation. Finally, based on results found in an experiment involving elevated acclimation temperature, the relationship between the number of antibody producing cells and fish body weight was examined. Plasma lysozyme concentrations and the number of pronephric leukocytes were both affected by acclimation to 21°C compared to 13°C. While a positive relationship was found between temperature and lysozyme, an inverse relationship was found between temperature and the number of pronephric leukocytes. Plasma lysozyme concentrations, the number of pronephric leukocytes, and the number of antibody producing cells did not respond to the stressor, and the combination of elevated temperature and stress did not have an additive effect on any of the physiological or immunological variables studied. Differences between controls and temperature-treated fish were not detected among individual time points throughout a temperature fluctuation experiment, despite overall responses in plasma lysozyme concentrations and the frequencies of circulating lymphocytes. The frequencies of circulating neutrophils and thrombocytes did not respond to the thermal stressor. Finally, a significant positive relationship was detected between the number of antibody producing cells (assessed by a hemolytic plaque assay) and body weight among non-stressed fish acclimated to 21°C and 13°C. Regardless of acclimation temperature, these results emphasize the importance of the standardization of fish size for immunological experiments. Results from this thesis suggest that some components of innate immunity are affected by elevated acclimation temperatures and that the adaptive immune system is affected by acclimation temperature differently in small and large fish. Title: The effects of elevated temperature and stress on immune function in juvenile chinook salmon (Oncorhynchus tshawytscha) Author: Harrahy, Laura Nicole Martini Stress, including extreme or rapidly changing temperatures, are known to have deleterious effects on fish health and physiology. This thesis examines the combined effects of elevated acclimation temperature and acute handling stress on the number of antibody producing cells, plasma lysozyme concentrations, and the number of pronephric leukocytes in juvenile chinook salmon (Oncorhynchus tshawytscha). An additional goal of this thesis was to explore the effects of a temperature fluctuation, as a potential instigator of thermal shock, on innate immunity in wild fall chinook salmon of the Columbia River, specifically to determine if there are effects on plasma lysozyme concentrations and on the frequencies of lymphocytes, neutrophils, and thrombocytes in circulation. Finally, based on results found in an experiment involving elevated acclimation temperature, the relationship between the number of antibody producing cells and fish body weight was examined. Plasma lysozyme concentrations and the number of pronephric leukocytes were both affected by acclimation to 21°C compared to 13°C. While a positive relationship was found between temperature and lysozyme, an inverse relationship was found between temperature and the number of pronephric leukocytes. Plasma lysozyme concentrations, the number of pronephric leukocytes, and the number of antibody producing cells did not respond to the stressor, and the combination of elevated temperature and stress did not have an additive effect on any of the physiological or immunological variables studied. Differences between controls and temperature-treated fish were not detected among individual time points throughout a temperature fluctuation experiment, despite overall responses in plasma lysozyme concentrations and the frequencies of circulating lymphocytes. The frequencies of circulating neutrophils and thrombocytes did not respond to the thermal stressor. Finally, a significant positive relationship was detected between the number of antibody producing cells (assessed by a hemolytic plaque assay) and body weight among non-stressed fish acclimated to 21°C and 13°C. Regardless of acclimation temperature, these results emphasize the importance of the standardization of fish size for immunological experiments. Results from this thesis suggest that some components of innate immunity are affected by elevated acclimation temperatures and that the adaptive immune system is affected by acclimation temperature differently in small and large fish. Close

• 49. [Article] Repeat temperature measurements in borehole GC-1, northwestern Utah: towards isolating a climate-change signal borehole temperature profiles

  Copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Repeat temperature measurements in borehole GC-1, northwestern Utah: towards isolating a climate-change signal borehole temperature profiles Author: Chapman, David S., Harris, Robert N. Copyrighted by American Geophysical Union Title: Repeat temperature measurements in borehole GC-1, northwestern Utah: towards isolating a climate-change signal borehole temperature profiles Author: Chapman, David S., Harris, Robert N. Copyrighted by American Geophysical Union Close

• 50. [Article] Design of an apparatus with controlled rates of temperature change for use in cold tolerance tests of conifers

  An apparatus was designed to permit freezing tests of needles and other tissue parts from coniferous trees under controlled rates of temperature change with time. The design is based on the principle of ...

  Citation × Citation Citation Abstract Copy Title: Design of an apparatus with controlled rates of temperature change for use in cold tolerance tests of conifers Author: Wessell, William James An apparatus was designed to permit freezing tests of needles and other tissue parts from coniferous trees under controlled rates of temperature change with time. The design is based on the principle of a balanced system of refrigeration demand and heat input to achieve a steady temperature state. The apparatus permits the operator to decrease temperatures from 0°C to -40°C at rates of 1, 2, 3, or 4°C per hour, to hold temperatures at the desired freezing level from 1 to 24 hours, and to increase to 0°C at rates of 1, 2, 3, or 4°C per hour. Temperatures achieved within the sample tubes are accurate to within ± 0. 9°C of the expected temperature. Title: Design of an apparatus with controlled rates of temperature change for use in cold tolerance tests of conifers Author: Wessell, William James An apparatus was designed to permit freezing tests of needles and other tissue parts from coniferous trees under controlled rates of temperature change with time. The design is based on the principle of a balanced system of refrigeration demand and heat input to achieve a steady temperature state. The apparatus permits the operator to decrease temperatures from 0°C to -40°C at rates of 1, 2, 3, or 4°C per hour, to hold temperatures at the desired freezing level from 1 to 24 hours, and to increase to 0°C at rates of 1, 2, 3, or 4°C per hour. Temperatures achieved within the sample tubes are accurate to within ± 0. 9°C of the expected temperature. Close