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• 1151. [Article] Modeling of the thermal behavior of irradiated sphere-pac mixed carbide fuel

  Several fuels are being investigated for fast breeder reactor applications. One promising concept is sphere-pac mixed carbide fuel. As a part of the development of this fuel concept it is necessary to ...

  Citation × Citation Citation Abstract Copy Title: Modeling of the thermal behavior of irradiated sphere-pac mixed carbide fuel Author: Ades, Maurice Several fuels are being investigated for fast breeder reactor applications. One promising concept is sphere-pac mixed carbide fuel. As a part of the development of this fuel concept it is necessary to determine the behavior of the irradiated fuel for safe and reliable operation on a sound economic basis. It is with the thermal aspect of this behavior that the current investigation is concerned. With a view to predicting the overall thermal behavior of the fuel pin during irradiation, theoretical models for various phenomena have been developed so that the various interrelated thermal components can be determined. These components include the thermal conductivity of the fuel in its initial configuration and during restructuring, the restructuring boundary, the temperature distribution, the extent of restructuring due to sintering, grain growth and porosity redistribution, fuel swelling and gas release, and the behavior of the fill gas in the free volume of the fuel pin. A two-dimensional unit cell model is developed to evaluate the effective conductivity of the fuel in its initial configuration. By implementing descriptions of sintering mechanisms on this model, the effective conductivity of the fuel during restructuring is evaluated. The restructuring boundary at each axial section is determined based on a thermal conductivity criteria. Under certain conditions the initial fuel configuration in the inner fuel regions is lost and is replaced by a porous pellet-shaped region. In the outer regions, however, fuel restructuring is not completed. The radial temperature distribution is evaluated by finite differences at a discrete number of axial sections. The local heat source has previously been computed for each section. Allowance is made for axial asymetry as well as power histories. The porosity redistribution in the inner fuel regions which have completed restructuring is evaluated by using a model describing the conservation of pores migrating up the thermal gradient. Swelling and gas release are modeled allowing for bubble nucleation, bubble and pore growth and re-solution of gas atoms. Gas release occurs through diffusion of individual gas atoms in the fuel matrix and follows the subsequent buildup of contiguous intergranular bubbles. Allowance is made for changes in the fuel microstructure due to restructuring and thermally-activated grain growth. Following gas release, the temperature and pressure of the free gas are evaluated. The models describing the various thermal behavior components were embodied into the computer code SPECKLE-I to predict the thermal response of the irradiated fuel pin. Results computed from SPECKLE -I indicate that the effective fuel conductivity increases with temperature, fill gas pressure and with the extent of sintering occuring between the fuel spheres. As gas release occurs, the effective conductivity is altered by the fission gas and the pressure buildup in the free volume. The fuel temperature, initially high, decreases significantly due to restructuring and is affected by the compensating effects of gas release and pressure buildup. The extent of restructuring and porosity redistribution increases with the fuel power. Fuel swelling and gas release are essentially controlled by the fuel microstructure and porosity. The results indicate that the extent of fuel restructuring affects swelling and gas release. As gas release occurs, the pressure of the fill gas increases significantly, its temperature remaining almost constant. Results from SPECKLE-I were compared with several fuel irradiations. The agreement obtained between predicted and measured thermal components suggests that SPECKLE-I is a valuable first step for evaluating the thermal response of irradiated sphere-pac mixed carbide fuel. The performance of this code, however, can be improved by further model development and experimental studies of phenomena not fully characterized. Title: Modeling of the thermal behavior of irradiated sphere-pac mixed carbide fuel Author: Ades, Maurice Several fuels are being investigated for fast breeder reactor applications. One promising concept is sphere-pac mixed carbide fuel. As a part of the development of this fuel concept it is necessary to determine the behavior of the irradiated fuel for safe and reliable operation on a sound economic basis. It is with the thermal aspect of this behavior that the current investigation is concerned. With a view to predicting the overall thermal behavior of the fuel pin during irradiation, theoretical models for various phenomena have been developed so that the various interrelated thermal components can be determined. These components include the thermal conductivity of the fuel in its initial configuration and during restructuring, the restructuring boundary, the temperature distribution, the extent of restructuring due to sintering, grain growth and porosity redistribution, fuel swelling and gas release, and the behavior of the fill gas in the free volume of the fuel pin. A two-dimensional unit cell model is developed to evaluate the effective conductivity of the fuel in its initial configuration. By implementing descriptions of sintering mechanisms on this model, the effective conductivity of the fuel during restructuring is evaluated. The restructuring boundary at each axial section is determined based on a thermal conductivity criteria. Under certain conditions the initial fuel configuration in the inner fuel regions is lost and is replaced by a porous pellet-shaped region. In the outer regions, however, fuel restructuring is not completed. The radial temperature distribution is evaluated by finite differences at a discrete number of axial sections. The local heat source has previously been computed for each section. Allowance is made for axial asymetry as well as power histories. The porosity redistribution in the inner fuel regions which have completed restructuring is evaluated by using a model describing the conservation of pores migrating up the thermal gradient. Swelling and gas release are modeled allowing for bubble nucleation, bubble and pore growth and re-solution of gas atoms. Gas release occurs through diffusion of individual gas atoms in the fuel matrix and follows the subsequent buildup of contiguous intergranular bubbles. Allowance is made for changes in the fuel microstructure due to restructuring and thermally-activated grain growth. Following gas release, the temperature and pressure of the free gas are evaluated. The models describing the various thermal behavior components were embodied into the computer code SPECKLE-I to predict the thermal response of the irradiated fuel pin. Results computed from SPECKLE -I indicate that the effective fuel conductivity increases with temperature, fill gas pressure and with the extent of sintering occuring between the fuel spheres. As gas release occurs, the effective conductivity is altered by the fission gas and the pressure buildup in the free volume. The fuel temperature, initially high, decreases significantly due to restructuring and is affected by the compensating effects of gas release and pressure buildup. The extent of restructuring and porosity redistribution increases with the fuel power. Fuel swelling and gas release are essentially controlled by the fuel microstructure and porosity. The results indicate that the extent of fuel restructuring affects swelling and gas release. As gas release occurs, the pressure of the fill gas increases significantly, its temperature remaining almost constant. Results from SPECKLE-I were compared with several fuel irradiations. The agreement obtained between predicted and measured thermal components suggests that SPECKLE-I is a valuable first step for evaluating the thermal response of irradiated sphere-pac mixed carbide fuel. The performance of this code, however, can be improved by further model development and experimental studies of phenomena not fully characterized. Close

• 1152. [Article] Genomic comparisons of seed-transmissible and non-seed-transmissible strains of cucumber mosaic virus

  A sensitive assay for the analysis of contaminating segments in pseudorecombinants constructed from a seed-transmissible (CVM-Pg) and a non-seed-transmissible (CMV-Le) strain of cucumber mosaic virus was ...

  Citation × Citation Citation Abstract Copy Title: Genomic comparisons of seed-transmissible and non-seed-transmissible strains of cucumber mosaic virus Author: Ried, Jeffrey L. A sensitive assay for the analysis of contaminating segments in pseudorecombinants constructed from a seed-transmissible (CVM-Pg) and a non-seed-transmissible (CMV-Le) strain of cucumber mosaic virus was developed using partial RNase T₁ digestion. Isolated genomic RNA segments produced unique digestion patterns when 3'- end labeled, treated with RNase T₁, and subjected to polyacrylamide gel electrophoresis. Although unique bands were present in these patterns, an overall similarity existed, resulting from putative insertions and deletions in the RNA of each strain. Northern blot hybridization studies of the homology between CMV-Pg and CMV-Le indicated that all 4 heterologous RNA segments contained sequences that were greater than 83% homologous. Homology between the total RNA from each strain was estimated at 70% when assayed by S₁ nuclease digestion following hybridization of RNA to a complementary DNA probe under stringent conditions. A comparison of the electrophoretic mobility of each RNA of both strains in agarose, glyoxal and polyacrylamide gels suggested that each segment was identical in size. RNA segments 1 and 2 when compared to the heterologous strain, however, had discernable differences in the secondary structure. A 5th RNA was detected in both strains. It migrated as two distinct bands when subjected to polyacrylamide gel electrophoresis, and was 3'-end labeled preferentially when present with segments 1-4. Complementary DNA synthesized from RNA 5 of one strain hybridized to segments 1-4 of both strains as determined by northern blot hybridization. RNA 5 of both strains produced identical patterns when subjected to partial RNase T₁ digestion, yet they differed significantly when compared to the digestion patterns from RNA 4 of the homologous strain. These results indicated that RNA 5 of both strains contained virtually identical nucleotide sequences and that they originated from RNA's 1-4, but not from the extreme 3'-terminus. Total CMV RNA, subjected to RNase H treatment after hybridization to a specific deoxyribohexanucleotide, produced two novel bands which were visualized by ethidium bromide staining. Double-stranded cDNA synthesized from RNA of each strain, cloned by blunt-end ligation, produced recombinant clones that contained only inserts of insignificant size. Title: Genomic comparisons of seed-transmissible and non-seed-transmissible strains of cucumber mosaic virus Author: Ried, Jeffrey L. A sensitive assay for the analysis of contaminating segments in pseudorecombinants constructed from a seed-transmissible (CVM-Pg) and a non-seed-transmissible (CMV-Le) strain of cucumber mosaic virus was developed using partial RNase T₁ digestion. Isolated genomic RNA segments produced unique digestion patterns when 3'- end labeled, treated with RNase T₁, and subjected to polyacrylamide gel electrophoresis. Although unique bands were present in these patterns, an overall similarity existed, resulting from putative insertions and deletions in the RNA of each strain. Northern blot hybridization studies of the homology between CMV-Pg and CMV-Le indicated that all 4 heterologous RNA segments contained sequences that were greater than 83% homologous. Homology between the total RNA from each strain was estimated at 70% when assayed by S₁ nuclease digestion following hybridization of RNA to a complementary DNA probe under stringent conditions. A comparison of the electrophoretic mobility of each RNA of both strains in agarose, glyoxal and polyacrylamide gels suggested that each segment was identical in size. RNA segments 1 and 2 when compared to the heterologous strain, however, had discernable differences in the secondary structure. A 5th RNA was detected in both strains. It migrated as two distinct bands when subjected to polyacrylamide gel electrophoresis, and was 3'-end labeled preferentially when present with segments 1-4. Complementary DNA synthesized from RNA 5 of one strain hybridized to segments 1-4 of both strains as determined by northern blot hybridization. RNA 5 of both strains produced identical patterns when subjected to partial RNase T₁ digestion, yet they differed significantly when compared to the digestion patterns from RNA 4 of the homologous strain. These results indicated that RNA 5 of both strains contained virtually identical nucleotide sequences and that they originated from RNA's 1-4, but not from the extreme 3'-terminus. Total CMV RNA, subjected to RNase H treatment after hybridization to a specific deoxyribohexanucleotide, produced two novel bands which were visualized by ethidium bromide staining. Double-stranded cDNA synthesized from RNA of each strain, cloned by blunt-end ligation, produced recombinant clones that contained only inserts of insignificant size. Close

• 1153. [Article] A comparative study of the isozymic proteins and the effect of metachemogenesis in the tissues of Periplaneta americana (L.)

  An attempt was made to demonstrate isozymic forms of esterase, MDH, LDH and GPDH and the variation in enzyme pattern with increasing age in the thoracic muscle, appendage muscle and hemolymph of the American ...

  Citation × Citation Citation Abstract Copy Title: A comparative study of the isozymic proteins and the effect of metachemogenesis in the tissues of Periplaneta americana (L.) Author: Beckendorf, Gerald Walter An attempt was made to demonstrate isozymic forms of esterase, MDH, LDH and GPDH and the variation in enzyme pattern with increasing age in the thoracic muscle, appendage muscle and hemolymph of the American cockroach, Periplaneta americana. Sampled specimens of both sexes were aged one through seven days, two weeks and one through six months. The proteins in the muscle homogenates and hemolymph aliquots were separated with the aid of polyacrylamide gel "disc" electrophoresis and it was discovered that the protein concentration should be kept below 4 mg/ml to enable proper photopolymerization of the sample gel. Isozyme patterns were localized on the gel by utilizing histochemical staining procedures. Esterase banding was more pronounced if the pH of the incubation mixture was lowered from 7.0 to 5.6. Muscle esterase patterns exhibited six fairly consistent major bands and a number of inconsistent minor bands. One effect of aging was the increased resolution of the fastest migrating band on the gel in the muscle of specimens older than seven days. Non-specific banding in the absence of substrate accounted for the majority of the dehydrogenase activity in the three tissues examined. Muscle MDH-specific patterns were characterized by two minor bands and a major band (R[subscript f] value approximately .39) consisting of three subbands. Muscle LDH and GPDH-specific patterns each possessed one specific band with R[supscript f] values of approximately .5 and .42 respectively. The density of the main GPDH band varied somewhat in muscle patterns with female thoracic muscle displaying little or no main band activity. Three major and three to six minor esterase bands were demonstrated in hemolymph. One MDH-specific band was found in hemolymph with an R[subscript f] value approximating that of the major three band complex in muscle. Although a number of non-specific bands were displayed in hemolymph, the patterns failed to disclose any LDH and GPDH-specific bands in hemolymph. Each of the patterns were evaluated as possible biochemical systematic indicators by examining the degree of stability with increasing age. Esterase patterns, although displaying stability in main bands, showed variation in appearance of minor bands for all three tissues. MDH in all three tissues and muscle LDH displayed a great deal of stability, qualifying these tissue enzymes as candidates for further systematic comparisons. The variation in the density of the GPDH band in muscle and the lack of specific LDH and GPDH banding in hemolymph makes these tissue enzymes of questionable value in future comparisons. Title: A comparative study of the isozymic proteins and the effect of metachemogenesis in the tissues of Periplaneta americana (L.) Author: Beckendorf, Gerald Walter An attempt was made to demonstrate isozymic forms of esterase, MDH, LDH and GPDH and the variation in enzyme pattern with increasing age in the thoracic muscle, appendage muscle and hemolymph of the American cockroach, Periplaneta americana. Sampled specimens of both sexes were aged one through seven days, two weeks and one through six months. The proteins in the muscle homogenates and hemolymph aliquots were separated with the aid of polyacrylamide gel "disc" electrophoresis and it was discovered that the protein concentration should be kept below 4 mg/ml to enable proper photopolymerization of the sample gel. Isozyme patterns were localized on the gel by utilizing histochemical staining procedures. Esterase banding was more pronounced if the pH of the incubation mixture was lowered from 7.0 to 5.6. Muscle esterase patterns exhibited six fairly consistent major bands and a number of inconsistent minor bands. One effect of aging was the increased resolution of the fastest migrating band on the gel in the muscle of specimens older than seven days. Non-specific banding in the absence of substrate accounted for the majority of the dehydrogenase activity in the three tissues examined. Muscle MDH-specific patterns were characterized by two minor bands and a major band (R[subscript f] value approximately .39) consisting of three subbands. Muscle LDH and GPDH-specific patterns each possessed one specific band with R[supscript f] values of approximately .5 and .42 respectively. The density of the main GPDH band varied somewhat in muscle patterns with female thoracic muscle displaying little or no main band activity. Three major and three to six minor esterase bands were demonstrated in hemolymph. One MDH-specific band was found in hemolymph with an R[subscript f] value approximating that of the major three band complex in muscle. Although a number of non-specific bands were displayed in hemolymph, the patterns failed to disclose any LDH and GPDH-specific bands in hemolymph. Each of the patterns were evaluated as possible biochemical systematic indicators by examining the degree of stability with increasing age. Esterase patterns, although displaying stability in main bands, showed variation in appearance of minor bands for all three tissues. MDH in all three tissues and muscle LDH displayed a great deal of stability, qualifying these tissue enzymes as candidates for further systematic comparisons. The variation in the density of the GPDH band in muscle and the lack of specific LDH and GPDH banding in hemolymph makes these tissue enzymes of questionable value in future comparisons. Close

• 1154. [Article] Development and use of satellite-derived sea-surface temperature data for the nearshore North Pacific and Arctic Oceans : temperature pattern analysis and implications for climate change at ecoregional scale

  The quantification and description of sea surface temperature (SST) is critically important because it can influence the distribution, migration, and invasion of marine species; furthermore, SSTs are expected ...

  Citation × Citation Citation Abstract Copy Title: Development and use of satellite-derived sea-surface temperature data for the nearshore North Pacific and Arctic Oceans : temperature pattern analysis and implications for climate change at ecoregional scale Author: Payne, Meredith C. The quantification and description of sea surface temperature (SST) is critically important because it can influence the distribution, migration, and invasion of marine species; furthermore, SSTs are expected to be affected by climate change. Recent research indicates that there has been a warming trend in ocean temperatures over the last 50 years. Hence, we sought to identify and demonstrate how a particularly germane SST dataset can be used within the scope of global climate change research. For this project we assembled a 29-year nearshore time series of mean monthly SSTs along the North Pacific coastline, as well as mean monthly SSTs for ice-free regions of the Arctic, using remotely-sensed satellite data collected with the Advanced Very High Resolution Radiometer (AVHRR) instrument. By providing detailed information concerning both dataset generation and data limitations, we aimed to make these data comprehensible to an expanded audience concentrating on life sciences rather than the traditionally physical science-based community. Furthermore, by making these data freely and publically available in multiple formats, including GIS (geographic information systems) layers, we expand their visibility and the extent of their use. We then used the dataset to describe SST patterns of nearshore (< 20 km offshore) regions of 16 North Pacific ecoregions, and of ice-free regions of 20 Arctic ecoregions, as delineated by the Marine Ecoregions of the World (MEOW) hierarchical schema. Our work creates a better understanding of present temperature regimes in these critically sensitive areas, from which we can draw several basic conclusions. 1) AVHRR SST measurements alone are sufficient to identify temperature patterns pertinent to determining health of ecosystems; 2) Within the nearshore North Pacific, ecoregions along the California Current System are most vulnerable to habitat-altering SST changes; 3) sea ice distribution is a major factor affecting SSTs in Arctic ecoregions, causing concern for the welfare of Arctic species. Title: Development and use of satellite-derived sea-surface temperature data for the nearshore North Pacific and Arctic Oceans : temperature pattern analysis and implications for climate change at ecoregional scale Author: Payne, Meredith C. The quantification and description of sea surface temperature (SST) is critically important because it can influence the distribution, migration, and invasion of marine species; furthermore, SSTs are expected to be affected by climate change. Recent research indicates that there has been a warming trend in ocean temperatures over the last 50 years. Hence, we sought to identify and demonstrate how a particularly germane SST dataset can be used within the scope of global climate change research. For this project we assembled a 29-year nearshore time series of mean monthly SSTs along the North Pacific coastline, as well as mean monthly SSTs for ice-free regions of the Arctic, using remotely-sensed satellite data collected with the Advanced Very High Resolution Radiometer (AVHRR) instrument. By providing detailed information concerning both dataset generation and data limitations, we aimed to make these data comprehensible to an expanded audience concentrating on life sciences rather than the traditionally physical science-based community. Furthermore, by making these data freely and publically available in multiple formats, including GIS (geographic information systems) layers, we expand their visibility and the extent of their use. We then used the dataset to describe SST patterns of nearshore (< 20 km offshore) regions of 16 North Pacific ecoregions, and of ice-free regions of 20 Arctic ecoregions, as delineated by the Marine Ecoregions of the World (MEOW) hierarchical schema. Our work creates a better understanding of present temperature regimes in these critically sensitive areas, from which we can draw several basic conclusions. 1) AVHRR SST measurements alone are sufficient to identify temperature patterns pertinent to determining health of ecosystems; 2) Within the nearshore North Pacific, ecoregions along the California Current System are most vulnerable to habitat-altering SST changes; 3) sea ice distribution is a major factor affecting SSTs in Arctic ecoregions, causing concern for the welfare of Arctic species. Close

• 1155. [Article] The life history of Nectobrachia indivisa Fraser, 1920 (Copepoda : Lernaeopodoida) a parasite of the starry flounder

  The stages in the life history of the parasitic copepod Nectobrachia indivisa Fraser, 1920, have been described. The adult female lives permanently attached to the gills of the starry flounder, Platichthys ...

  Citation × Citation Citation Abstract Copy Title: The life history of Nectobrachia indivisa Fraser, 1920 (Copepoda : Lernaeopodoida) a parasite of the starry flounder Author: Wilkes, Stanley Northrup The stages in the life history of the parasitic copepod Nectobrachia indivisa Fraser, 1920, have been described. The adult female lives permanently attached to the gills of the starry flounder, Platichthys stellatus (Pallas, 1811) Girard, 1854. The adult male is a dwarf, which usually lives attached to the genital process of the female. The eggs hatch into free-swimming, but relatively inactive nauplii. They usually molt after 20-40 minutes into vigorous free-swimming copepodid larvae. The copepodid either remains in the gill chamber of the original host or migrates to a new one of the same species. After about three days it attaches itself by means of a chitinous disc and filament to the cuticle of an adult female copepod, usually Nectobrachia indivisa but occasionally Acanthochondria rectangularis (Fraser, 1920) Oakley, 1927, or Lepeophtheirus parvicrurus Fraser, 1920. A withdrawal of the protoplasm from the extremities into the cephalothorax takes place in the copepodid. A new skin forms around the protoplasmic mass and within the old copepodid skin. This marks the advent of the pupal stage. The old copepodid skin may or may not be cast, but the pupa continues to use the original attachment filament. The pupa molts into either an immature female or a nearly mature male. The male soon seeks out an attached female of the same species, matures, and copulates. The post-pupal female remains connected to the pupal case for a period and then attaches permanently to a gill filament of the host by means of an eight-branched bulla. After changing considerably, both in size and morphology, the female becomes sexually mature. Mating occurs and fertile eggs are deposited into the egg sacs. The orientation of embryos in the egg sacs is with head to the inside, opposite to that of Achtheres ambloplitis Kellicott, 1880. Wilson proposed that oxygen supply is the factor in the latter, while ease of hatching may be the advantage of this arrangement for Nectobrachia indivisa. The nauplius differs from all other lernaeopodid nauplii in having mandibles and non-plumose setae. A long club-like process is present on each of the first antennae of the copepodid stage. It may have a sensory function involving taste or smell or both. The attachment of the copepodid appears to require a chitinous substrate. Possible methods of attachment are discussed. The formation of a discrete pupal skin is recognized in this family and the maxillipedal sleeves are described, both for the first time. The latter function as a holdfast for the post-pupal female. The first maxillipeds appear to play an active part in the removal of the bulla from the cephalic region of the post-pupal female. Possible attachment methods are considered and growth after the pupal molt is discussed. There is some evidence in favor of partial molting. Title: The life history of Nectobrachia indivisa Fraser, 1920 (Copepoda : Lernaeopodoida) a parasite of the starry flounder Author: Wilkes, Stanley Northrup The stages in the life history of the parasitic copepod Nectobrachia indivisa Fraser, 1920, have been described. The adult female lives permanently attached to the gills of the starry flounder, Platichthys stellatus (Pallas, 1811) Girard, 1854. The adult male is a dwarf, which usually lives attached to the genital process of the female. The eggs hatch into free-swimming, but relatively inactive nauplii. They usually molt after 20-40 minutes into vigorous free-swimming copepodid larvae. The copepodid either remains in the gill chamber of the original host or migrates to a new one of the same species. After about three days it attaches itself by means of a chitinous disc and filament to the cuticle of an adult female copepod, usually Nectobrachia indivisa but occasionally Acanthochondria rectangularis (Fraser, 1920) Oakley, 1927, or Lepeophtheirus parvicrurus Fraser, 1920. A withdrawal of the protoplasm from the extremities into the cephalothorax takes place in the copepodid. A new skin forms around the protoplasmic mass and within the old copepodid skin. This marks the advent of the pupal stage. The old copepodid skin may or may not be cast, but the pupa continues to use the original attachment filament. The pupa molts into either an immature female or a nearly mature male. The male soon seeks out an attached female of the same species, matures, and copulates. The post-pupal female remains connected to the pupal case for a period and then attaches permanently to a gill filament of the host by means of an eight-branched bulla. After changing considerably, both in size and morphology, the female becomes sexually mature. Mating occurs and fertile eggs are deposited into the egg sacs. The orientation of embryos in the egg sacs is with head to the inside, opposite to that of Achtheres ambloplitis Kellicott, 1880. Wilson proposed that oxygen supply is the factor in the latter, while ease of hatching may be the advantage of this arrangement for Nectobrachia indivisa. The nauplius differs from all other lernaeopodid nauplii in having mandibles and non-plumose setae. A long club-like process is present on each of the first antennae of the copepodid stage. It may have a sensory function involving taste or smell or both. The attachment of the copepodid appears to require a chitinous substrate. Possible methods of attachment are discussed. The formation of a discrete pupal skin is recognized in this family and the maxillipedal sleeves are described, both for the first time. The latter function as a holdfast for the post-pupal female. The first maxillipeds appear to play an active part in the removal of the bulla from the cephalic region of the post-pupal female. Possible attachment methods are considered and growth after the pupal molt is discussed. There is some evidence in favor of partial molting. Close

• 1156. [Article] Gene networks during cardiogenesis and skeletal myogenesis

  Organismal development requires a precisely orchestrated transcriptional program to correctly deploy genetic information into the genome. This process requires sophisticated gene regulatory networks at ...

  Citation × Citation Citation Abstract Copy Title: Gene networks during cardiogenesis and skeletal myogenesis Author: Ma, Hsiao-Yen Organismal development requires a precisely orchestrated transcriptional program to correctly deploy genetic information into the genome. This process requires sophisticated gene regulatory networks at multiple spatial and temporal levels from early embryonic development to adult physiological conditions. Molecular differences that define cell types are set up during the pattern formation phase of development. Selective gene expression provides molecular markers such as sequence specific DNA-binding transcription factors (SSTFs) to define cell types. Homeodomain transcription factors are essential for embryonic pattern formation and cell specification and therefore can affect several mechanistically distinct aspects of organ development. The Pitx2 homeobox gene is expressed in the lateral plate mesoderm and it is involved in cardiac and skeletal muscle development. Mutations of Pitx2 are associated with the human Axenfeld-Rieger syndrome. Pitx2 null mice die at embryonic day 13.5 and exhibit un-septated atria and outflow tract that leads to deformed valves and arrythmias. Pitx2 promotes the proliferation of the branchial arch mesoderm-derived cells and their remodeling process, the epithelial-mesenchymal transition, to form the outflow tract cushions by influencing the expression of SSTFs in the cardiac mesoderm. Pitx2 is expressed in skeletal muscle cells from their time as progenitors until they form mature muscle groups. In Pitx2 null mutant mice the skeletal muscles have been specified, the muscles were formed but their higher order assembly was disrupted. Pitx2 was a key player of the embryonic muscle progenitors as they transition to the fetal state. Embryonic muscle progenitors were able to delaminate from the dermomyotome and migrate to the forelimb pre-patterned anlagen but were not fast to transition to the fetal state, as their G1 phase was arrested and their motility was disrupted. We have developed a Pitx2 conditional genetic system that eliminates the early cause of death and allows us to investigate the role Pitx2 at later stages. The molecular mechanisms of muscle regeneration in adults share many characteristics with the myogenic programs that generate skeletal muscle during development. These studies will enhance the molecular understanding of myogenic development and generate muscle-impaired mouse lines for drug and regeneration studies. Title: Gene networks during cardiogenesis and skeletal myogenesis Author: Ma, Hsiao-Yen Organismal development requires a precisely orchestrated transcriptional program to correctly deploy genetic information into the genome. This process requires sophisticated gene regulatory networks at multiple spatial and temporal levels from early embryonic development to adult physiological conditions. Molecular differences that define cell types are set up during the pattern formation phase of development. Selective gene expression provides molecular markers such as sequence specific DNA-binding transcription factors (SSTFs) to define cell types. Homeodomain transcription factors are essential for embryonic pattern formation and cell specification and therefore can affect several mechanistically distinct aspects of organ development. The Pitx2 homeobox gene is expressed in the lateral plate mesoderm and it is involved in cardiac and skeletal muscle development. Mutations of Pitx2 are associated with the human Axenfeld-Rieger syndrome. Pitx2 null mice die at embryonic day 13.5 and exhibit un-septated atria and outflow tract that leads to deformed valves and arrythmias. Pitx2 promotes the proliferation of the branchial arch mesoderm-derived cells and their remodeling process, the epithelial-mesenchymal transition, to form the outflow tract cushions by influencing the expression of SSTFs in the cardiac mesoderm. Pitx2 is expressed in skeletal muscle cells from their time as progenitors until they form mature muscle groups. In Pitx2 null mutant mice the skeletal muscles have been specified, the muscles were formed but their higher order assembly was disrupted. Pitx2 was a key player of the embryonic muscle progenitors as they transition to the fetal state. Embryonic muscle progenitors were able to delaminate from the dermomyotome and migrate to the forelimb pre-patterned anlagen but were not fast to transition to the fetal state, as their G1 phase was arrested and their motility was disrupted. We have developed a Pitx2 conditional genetic system that eliminates the early cause of death and allows us to investigate the role Pitx2 at later stages. The molecular mechanisms of muscle regeneration in adults share many characteristics with the myogenic programs that generate skeletal muscle during development. These studies will enhance the molecular understanding of myogenic development and generate muscle-impaired mouse lines for drug and regeneration studies. Close

• 1157. [Article] Walking the narrow path : narratives of migration and mental health among Saudi Arabian women at Oregon State University

  Since the inauguration of the King Abdullah-Aziz Foreign Scholarship Program in 2005, the number of Saudi university students in the United States has increased exponentially, and an unprecedented amount ...

  Citation × Citation Citation Abstract Copy Title: Walking the narrow path : narratives of migration and mental health among Saudi Arabian women at Oregon State University Author: Gentry, Kristen Elizabeth Since the inauguration of the King Abdullah-Aziz Foreign Scholarship Program in 2005, the number of Saudi university students in the United States has increased exponentially, and an unprecedented amount of Saudi women are seeking international degrees. The absence of scholarly research within these women’s home and host countries highlights the need for an ethnographic account of their transnational experiences, which can elucidate ways in which knowledge, values, and customs are in a constant process of contextual negotiation. This in turn influences available sources of social support and psychological well-being. Drawing on data from free-lists, a focus group, and in-depth semi-structured interviews, this ethnographic research aims to uncover and examine the social determinants of psychological well-being as described by the narrative experiences of Saudi Arabian women studying at Oregon State University. After providing a detailed analysis of specific sociocultural structures operating in these women's lives, two sides qualifying Saudi Arabian women's experiences are examined: stakes of their international education projects and challenges in maintaining good mental health. These stakes, formed by sociocultural structures, circumscribe their experiences, decisions, and behavior in the U.S., where they must navigate through new challenges and sources of distress. The challenges they face cause distress, but also delineate possible sources of support and create avenues for agency. Finally, this thesis is concluded by recommending applications for mental health care providers and examining macro-level theoretical underpinnings of social determinants of psychological well-being. Title: Walking the narrow path : narratives of migration and mental health among Saudi Arabian women at Oregon State University Author: Gentry, Kristen Elizabeth Since the inauguration of the King Abdullah-Aziz Foreign Scholarship Program in 2005, the number of Saudi university students in the United States has increased exponentially, and an unprecedented amount of Saudi women are seeking international degrees. The absence of scholarly research within these women’s home and host countries highlights the need for an ethnographic account of their transnational experiences, which can elucidate ways in which knowledge, values, and customs are in a constant process of contextual negotiation. This in turn influences available sources of social support and psychological well-being. Drawing on data from free-lists, a focus group, and in-depth semi-structured interviews, this ethnographic research aims to uncover and examine the social determinants of psychological well-being as described by the narrative experiences of Saudi Arabian women studying at Oregon State University. After providing a detailed analysis of specific sociocultural structures operating in these women's lives, two sides qualifying Saudi Arabian women's experiences are examined: stakes of their international education projects and challenges in maintaining good mental health. These stakes, formed by sociocultural structures, circumscribe their experiences, decisions, and behavior in the U.S., where they must navigate through new challenges and sources of distress. The challenges they face cause distress, but also delineate possible sources of support and create avenues for agency. Finally, this thesis is concluded by recommending applications for mental health care providers and examining macro-level theoretical underpinnings of social determinants of psychological well-being. Close

• 1158. [Article] Ecology of mites on pomaceous fruit trees and related wild hosts in Hood River Valley

  The ecological interrelationships of mites occurring in and near the Hood River Valley, Oregon, pome fruit orchards were investigated to determine the possibility of an integrated control program using ...

  Citation × Citation Citation Abstract Copy Title: Ecology of mites on pomaceous fruit trees and related wild hosts in Hood River Valley Author: Jorgensen, Clive Darrel The ecological interrelationships of mites occurring in and near the Hood River Valley, Oregon, pome fruit orchards were investigated to determine the possibility of an integrated control program using the species already present. Survey sampling methods were used to study mites on wild hosts (Crataegus douglasii Lindl., Crataegus columbiana Howell, and Amelanchier florida Lindl.) related to pome fruits, abandoned and commercial apple and pear orchards, and soil with its cover in abandoned apple and pear orchards. Distribution of mites among the orchards, within the trees, upon the leaves, and among certain varieties was also investigated. Mites were collected from leaves, spurs and stems, bark, and soil and cover in the orchards; and from leaves, and spurs and stems of the wild hosts. Mites frequently collected from the wild hosts were Bryobia arborea Morgan and Anderson, Panonychus ulmi (Koch), Tydeus californicus (Banks), Tydeus zempoalensis Baker, Typhlodromus rhenanus (Oudms.), and Typhlodromus mcgregori Chant. Eotetranychus carpini (Ewing), Eotetranychus willamettei McG., Balaustium sp., Typhlodromus anachialus (Kennett), Typhlodromus arboreus (Chant), and Typhlodromus crataegi Jorgensen and Chant were collected less frequently. Crataegus columbiana was the preferred habitat for Tydeus californicus, whereas Tydeus zempoalensis preferred Crataegus douglasii. The nature of these preferences is unknown, since both species were apparently non-phytophagous. Pest species (Panonychus ulmi and Bryobia arborea) were abundant on wild host plots only when these were near orchards infested with the same pests. Wild hosts are not considered important sources of pests or predacious species far adjacent orchards at the present time. Forty-seven species of mites were collected from the soil and cover, of which only three (Tetranychus telarius (L), Balaustium sp., Typhlodromus rhenanus) were also abundant on the trees. Since the populations on the trees are apparently isolated from those on the soil and cover, it was concluded that the two populations are independent of each other. Only if pests, such as Tetranychus telarius and predators such as Balaustium sp., which migrate to and from the trees, become numerous in the orchards will the populations on the soil and cover interact directly with populations on the trees. Species which were associated with abandoned and semi-commercial orchards were Bryobia arborea, Panonychus ulmi, Eotetranychus carpini, Tetranychus telarius, Tydeus californicus, Tydeus zempoalensis, Balaustium sp., Mediolata mall, Typhlodromus mcgregori, Typhlodromus rhenanus, and several less abundant species. Mite complexes among the orchards varied markedly, resulting in rather diverse species associations in different orchards. This was particularly true with respect to the predators. Some predators (Typhlodromus rhenanus and Typhlodromus mcgregori) that were abundant in one orchard were virtually absent from others. Also, Tydeus californicus preferred abandoned pear orchards to apple, whereas Tydeus zempoalensis preferred apple. Distributions of predators were never well syncronized with those of the pests, especially Panonychus ulmi. This was true, regardless of what distribution was considered; seasonal, among the orchards, within the trees, upon the leaves, or between mature and immature leaves. As a result of these discrepancies, it was concluded that predation by Typhlodromus rhenanus, Typhlodromus mcgregori, Mediolata mali (Ewing), and Balaustium sp. was not efficient on Panonychus ulmi and Bryobia arborea; but, efficiency was probably higher on Eotetranychus carpini, Eotetranychus willamettei, and Tetranychus telarius. These same discrepancies probably resulted in the lack of interactions between predators and prey that could be identified as causative action on the part of the predators. Interactions between predators and prey were not sufficient to be interpreted as being caused by predation. The data obtained during this study led to the conclusion that the acarine predators now present would not be particularly beneficial in an integrated control program. Title: Ecology of mites on pomaceous fruit trees and related wild hosts in Hood River Valley Author: Jorgensen, Clive Darrel The ecological interrelationships of mites occurring in and near the Hood River Valley, Oregon, pome fruit orchards were investigated to determine the possibility of an integrated control program using the species already present. Survey sampling methods were used to study mites on wild hosts (Crataegus douglasii Lindl., Crataegus columbiana Howell, and Amelanchier florida Lindl.) related to pome fruits, abandoned and commercial apple and pear orchards, and soil with its cover in abandoned apple and pear orchards. Distribution of mites among the orchards, within the trees, upon the leaves, and among certain varieties was also investigated. Mites were collected from leaves, spurs and stems, bark, and soil and cover in the orchards; and from leaves, and spurs and stems of the wild hosts. Mites frequently collected from the wild hosts were Bryobia arborea Morgan and Anderson, Panonychus ulmi (Koch), Tydeus californicus (Banks), Tydeus zempoalensis Baker, Typhlodromus rhenanus (Oudms.), and Typhlodromus mcgregori Chant. Eotetranychus carpini (Ewing), Eotetranychus willamettei McG., Balaustium sp., Typhlodromus anachialus (Kennett), Typhlodromus arboreus (Chant), and Typhlodromus crataegi Jorgensen and Chant were collected less frequently. Crataegus columbiana was the preferred habitat for Tydeus californicus, whereas Tydeus zempoalensis preferred Crataegus douglasii. The nature of these preferences is unknown, since both species were apparently non-phytophagous. Pest species (Panonychus ulmi and Bryobia arborea) were abundant on wild host plots only when these were near orchards infested with the same pests. Wild hosts are not considered important sources of pests or predacious species far adjacent orchards at the present time. Forty-seven species of mites were collected from the soil and cover, of which only three (Tetranychus telarius (L), Balaustium sp., Typhlodromus rhenanus) were also abundant on the trees. Since the populations on the trees are apparently isolated from those on the soil and cover, it was concluded that the two populations are independent of each other. Only if pests, such as Tetranychus telarius and predators such as Balaustium sp., which migrate to and from the trees, become numerous in the orchards will the populations on the soil and cover interact directly with populations on the trees. Species which were associated with abandoned and semi-commercial orchards were Bryobia arborea, Panonychus ulmi, Eotetranychus carpini, Tetranychus telarius, Tydeus californicus, Tydeus zempoalensis, Balaustium sp., Mediolata mall, Typhlodromus mcgregori, Typhlodromus rhenanus, and several less abundant species. Mite complexes among the orchards varied markedly, resulting in rather diverse species associations in different orchards. This was particularly true with respect to the predators. Some predators (Typhlodromus rhenanus and Typhlodromus mcgregori) that were abundant in one orchard were virtually absent from others. Also, Tydeus californicus preferred abandoned pear orchards to apple, whereas Tydeus zempoalensis preferred apple. Distributions of predators were never well syncronized with those of the pests, especially Panonychus ulmi. This was true, regardless of what distribution was considered; seasonal, among the orchards, within the trees, upon the leaves, or between mature and immature leaves. As a result of these discrepancies, it was concluded that predation by Typhlodromus rhenanus, Typhlodromus mcgregori, Mediolata mali (Ewing), and Balaustium sp. was not efficient on Panonychus ulmi and Bryobia arborea; but, efficiency was probably higher on Eotetranychus carpini, Eotetranychus willamettei, and Tetranychus telarius. These same discrepancies probably resulted in the lack of interactions between predators and prey that could be identified as causative action on the part of the predators. Interactions between predators and prey were not sufficient to be interpreted as being caused by predation. The data obtained during this study led to the conclusion that the acarine predators now present would not be particularly beneficial in an integrated control program. Close

• 1159. [Article] The Relationship Between Immigrant Status and Secondary and Postsecondary Attainment in Secondary Students

  The American School Counseling Association’s Code of Ethics states that counselors and counselor trainees must be competent providers of multicultural counseling, able to practice effectively with clients ...

  Citation × Citation Citation Abstract Copy Title: The Relationship Between Immigrant Status and Secondary and Postsecondary Attainment in Secondary Students Author: Haviland, Samantha L. The American School Counseling Association’s Code of Ethics states that counselors and counselor trainees must be competent providers of multicultural counseling, able to practice effectively with clients whose identities differ from their own. Pre-service school counselors receive very little training around immigration status and how to work with clients who migrate from different countries and cultures. School counselors, counselor educators and pre-service counselors are also asked to seek out current, relevant research to provide a basis for the interventions and treatment offered to clients. Recent literature in school counseling has identified educational gaps among individuals who identify as, or are identified as, ethnic minorities. Higher rates of high school dropout and lower rates of postsecondary education matriculation have been found in immigrant samples as compared to nonimmigrant samples. However, existing articles are limited by: (a) sample sizes, (b) access to secondary student data, and (c) limited school counselor interventions. Additionally, school counselors and counselor educators have not researched these differences in immigration and graduation or postsecondary aspirations. To address this gap three research questions were explored. The first question asked what was the relationship between certain resiliency skills and immigrant status of middle school students. Results indicated a small but significant relationship between immigrant status and the skills of wellbeing and understanding the importance of education. The second research question queried as to whether a relationship exists between immigrant student contact with a school counselor and college as a post-secondary plan in high school. The results indicated a significant but small negative relationship between immigrant students meeting with a school counselor on career and college planning and college as a postsecondary plan. The third research question inquired as to whether a relationship exists between immigrant status and utilization of a school counselor for career and college planning in high school. The results indicated a small but significant positive relationship between immigrant status and utilization of a school counselor for career and college planning. The primary implication that emerged from the aforementioned research was that school counselors should be especially in tuned to the needs of immigrant students as their skills and needs may differ from native born students. Additionally, students who immigrate should be given an opportunity to meet individually with their school counselor for both wellbeing and career and college related topics. Title: The Relationship Between Immigrant Status and Secondary and Postsecondary Attainment in Secondary Students Author: Haviland, Samantha L. The American School Counseling Association’s Code of Ethics states that counselors and counselor trainees must be competent providers of multicultural counseling, able to practice effectively with clients whose identities differ from their own. Pre-service school counselors receive very little training around immigration status and how to work with clients who migrate from different countries and cultures. School counselors, counselor educators and pre-service counselors are also asked to seek out current, relevant research to provide a basis for the interventions and treatment offered to clients. Recent literature in school counseling has identified educational gaps among individuals who identify as, or are identified as, ethnic minorities. Higher rates of high school dropout and lower rates of postsecondary education matriculation have been found in immigrant samples as compared to nonimmigrant samples. However, existing articles are limited by: (a) sample sizes, (b) access to secondary student data, and (c) limited school counselor interventions. Additionally, school counselors and counselor educators have not researched these differences in immigration and graduation or postsecondary aspirations. To address this gap three research questions were explored. The first question asked what was the relationship between certain resiliency skills and immigrant status of middle school students. Results indicated a small but significant relationship between immigrant status and the skills of wellbeing and understanding the importance of education. The second research question queried as to whether a relationship exists between immigrant student contact with a school counselor and college as a post-secondary plan in high school. The results indicated a significant but small negative relationship between immigrant students meeting with a school counselor on career and college planning and college as a postsecondary plan. The third research question inquired as to whether a relationship exists between immigrant status and utilization of a school counselor for career and college planning in high school. The results indicated a small but significant positive relationship between immigrant status and utilization of a school counselor for career and college planning. The primary implication that emerged from the aforementioned research was that school counselors should be especially in tuned to the needs of immigrant students as their skills and needs may differ from native born students. Additionally, students who immigrate should be given an opportunity to meet individually with their school counselor for both wellbeing and career and college related topics. Close

• 1160. [Article] Spatial distribution and the probability of occurrence of beluga whales (Delphinapterus leucas) in Alaskan Arctic

  The known distribution of beluga whales ranges from sub-Arctic to Arctic waters where they migrate in pods in response to environmental factors such as the presence of sea ice and prey. This study uses ...

  Citation × Citation Citation Abstract Copy Title: Spatial distribution and the probability of occurrence of beluga whales (Delphinapterus leucas) in Alaskan Arctic Author: Romeo, Lucy F. The known distribution of beluga whales ranges from sub-Arctic to Arctic waters where they migrate in pods in response to environmental factors such as the presence of sea ice and prey. This study uses bivariate and multivariate analysis techniques to measure how environmental covariates are associated with the spatial-temporal distribution of beluga whales. Exploratory data analysis was used to determine the relationship among environmental covariates: bathymetry, slope, sea surface temperature, and distance to sea ice. Spatial analyses were used to determine the probability of occurrence of beluga whales in the northeastern Chukchi and southwestern Beaufort seas, based on each environmental covariate for the autumn months of the two study periods, from 2000 to 2006 and from 2008 to 2012. Findings from this study suggest that correlations exist between SST and distance to sea ice, and depth and distance to sea ice, and that beluga whales may prefer areas of relatively steep slope and associated increasing depth along the continental slope. Probability of occurrence maps were created for September and October for each year, based on beluga whale preference and avoidance for each environmental covariate. Areas of preference, or high probability of occurrence, had more beluga whale sightings than expected. And areas of avoidance, or low probability of occurrence, had less beluga whale sightings than expected. Model validation included randomly dividing observational data from September of 2011 into a training (70%) and testing (30%) dataset, then creating a probability of occurrence model based on the training dataset and comparing the results to the locations of the testing dataset. Outputs from the analyses can help guide studies of beluga environmental covariate preferences and the possible influences on their occurrence. Better understanding of the spatial distribution of beluga whales can provide a tool for better management practices. Improved practices in management and conservation of habitat for beluga whales will impact indigenous communities who rely on marine mammals as cultural and consumable resources. Title: Spatial distribution and the probability of occurrence of beluga whales (Delphinapterus leucas) in Alaskan Arctic Author: Romeo, Lucy F. The known distribution of beluga whales ranges from sub-Arctic to Arctic waters where they migrate in pods in response to environmental factors such as the presence of sea ice and prey. This study uses bivariate and multivariate analysis techniques to measure how environmental covariates are associated with the spatial-temporal distribution of beluga whales. Exploratory data analysis was used to determine the relationship among environmental covariates: bathymetry, slope, sea surface temperature, and distance to sea ice. Spatial analyses were used to determine the probability of occurrence of beluga whales in the northeastern Chukchi and southwestern Beaufort seas, based on each environmental covariate for the autumn months of the two study periods, from 2000 to 2006 and from 2008 to 2012. Findings from this study suggest that correlations exist between SST and distance to sea ice, and depth and distance to sea ice, and that beluga whales may prefer areas of relatively steep slope and associated increasing depth along the continental slope. Probability of occurrence maps were created for September and October for each year, based on beluga whale preference and avoidance for each environmental covariate. Areas of preference, or high probability of occurrence, had more beluga whale sightings than expected. And areas of avoidance, or low probability of occurrence, had less beluga whale sightings than expected. Model validation included randomly dividing observational data from September of 2011 into a training (70%) and testing (30%) dataset, then creating a probability of occurrence model based on the training dataset and comparing the results to the locations of the testing dataset. Outputs from the analyses can help guide studies of beluga environmental covariate preferences and the possible influences on their occurrence. Better understanding of the spatial distribution of beluga whales can provide a tool for better management practices. Improved practices in management and conservation of habitat for beluga whales will impact indigenous communities who rely on marine mammals as cultural and consumable resources. Close