Search

Search Results

• 41. [Article] Does temperature preference change in aging flies?

  We set out to see if a biomarker of aging in could be found in temperance preference since it was found previously to be a predictable circadian rhythm in young flies. Since flies live 70 days it can be ...

  Citation × Citation Citation Abstract Copy Title: Does temperature preference change in aging flies? Author: Giebultowicz, T., Chow, E., Chase, Teresa We set out to see if a biomarker of aging in could be found in temperance preference since it was found previously to be a predictable circadian rhythm in young flies. Since flies live 70 days it can be said that a day in the life of a fly is like a year in the life of a human. This is important because in our lab we use flies as a model organism for studying aging as to then apply to our understanding of human health and longevity. Currently most labs use over all lifespan as their biomarker of aging, but we need something that can be seen throughout the lifespan, not just at the end of it. We are always on the lookout for ways to see how aging effects the different conditions and genetic mutations we use. First we chose both wild types and genetic mutations to test for variation in results. We aged these flies at different intervals so as to have different ages to compare together. We further put these flies in alternating light-dark conditions to test together at different time points along the circadian 24 hour clock. The flies were tested in an apparatus that had a hot and cold side, with room temperature estimated in the middle along a temperature gradient that was established. There were 4 channels that separated the different groups of 50 individuals which labeled by their time of time, age, gender and genotype. After 30 minutes, a picture was taken to determine each of their temperature preference. No fly was retested and instead many bio repeats were used to establish a trend. Each fly was given a xy coordinate which a formula and computer program assigned a temperature to each. This data was averaged using statistical test and used to plot graphs of how the rhythm of temperature preference changed from young and old, and compared to the previously reported data. Title: Does temperature preference change in aging flies? Author: Giebultowicz, T., Chow, E., Chase, Teresa We set out to see if a biomarker of aging in could be found in temperance preference since it was found previously to be a predictable circadian rhythm in young flies. Since flies live 70 days it can be said that a day in the life of a fly is like a year in the life of a human. This is important because in our lab we use flies as a model organism for studying aging as to then apply to our understanding of human health and longevity. Currently most labs use over all lifespan as their biomarker of aging, but we need something that can be seen throughout the lifespan, not just at the end of it. We are always on the lookout for ways to see how aging effects the different conditions and genetic mutations we use. First we chose both wild types and genetic mutations to test for variation in results. We aged these flies at different intervals so as to have different ages to compare together. We further put these flies in alternating light-dark conditions to test together at different time points along the circadian 24 hour clock. The flies were tested in an apparatus that had a hot and cold side, with room temperature estimated in the middle along a temperature gradient that was established. There were 4 channels that separated the different groups of 50 individuals which labeled by their time of time, age, gender and genotype. After 30 minutes, a picture was taken to determine each of their temperature preference. No fly was retested and instead many bio repeats were used to establish a trend. Each fly was given a xy coordinate which a formula and computer program assigned a temperature to each. This data was averaged using statistical test and used to plot graphs of how the rhythm of temperature preference changed from young and old, and compared to the previously reported data. Close

• 42. [Article] Exploring reproductive signaling using nonconventional aquatic models: aging and reproductive function in killifish and sea anemones

  Aquatic animals possess surprising similarities to humans in reproductive signaling that are simplified or elaborated for life underwater, making them useful for studying reproductive control. In this ...

  Citation × Citation Citation Abstract Copy Title: Exploring reproductive signaling using nonconventional aquatic models: aging and reproductive function in killifish and sea anemones Author: Ferguson, Lindsey G. Aquatic animals possess surprising similarities to humans in reproductive signaling that are simplified or elaborated for life underwater, making them useful for studying reproductive control. In this thesis, killifish and sea anemones are used as models for reproductive function and aging. The aging model Nothobranchius (killifish) was used to investigate circadian rhythms and clock gene expression in reproductive tissues, and effects of the anti-aging compound resveratrol (RSV) were examined to elucidate the role of clock genes in fertility. Weak connections were found between gonadal clock gene expression and age, and RSV altered expression over time and shifted rhythmic patterns in old fish, suggesting that it may modulate circadian rhythms with age. Additionally, to understand the physiological mechanisms behind coral spawning for conservation and elucidate hormonal evolution, functions of the cnidarian leucine-rich repeat-containing G protein-coupled receptor LGRA2 were investigated in the model sea anemone Aiptasia pallida. LGRA2 was expressed near gonadal regions of sexually developed sea anemones, activated by gonadotropins, and modulated by estrogen, indicating that it is involved in regulating reproduction similarly to its mammalian homologs luteinizing hormone receptor and follicle stimulating hormone receptor. These projects together provide a One Health view of reproductive signaling and aging. Title: Exploring reproductive signaling using nonconventional aquatic models: aging and reproductive function in killifish and sea anemones Author: Ferguson, Lindsey G. Aquatic animals possess surprising similarities to humans in reproductive signaling that are simplified or elaborated for life underwater, making them useful for studying reproductive control. In this thesis, killifish and sea anemones are used as models for reproductive function and aging. The aging model Nothobranchius (killifish) was used to investigate circadian rhythms and clock gene expression in reproductive tissues, and effects of the anti-aging compound resveratrol (RSV) were examined to elucidate the role of clock genes in fertility. Weak connections were found between gonadal clock gene expression and age, and RSV altered expression over time and shifted rhythmic patterns in old fish, suggesting that it may modulate circadian rhythms with age. Additionally, to understand the physiological mechanisms behind coral spawning for conservation and elucidate hormonal evolution, functions of the cnidarian leucine-rich repeat-containing G protein-coupled receptor LGRA2 were investigated in the model sea anemone Aiptasia pallida. LGRA2 was expressed near gonadal regions of sexually developed sea anemones, activated by gonadotropins, and modulated by estrogen, indicating that it is involved in regulating reproduction similarly to its mammalian homologs luteinizing hormone receptor and follicle stimulating hormone receptor. These projects together provide a One Health view of reproductive signaling and aging. Close

• 43. [Article] The effects of population age on trade

  This paper empirically examines the effects of population aging on international trade using a cross-country panel data set for a select group of 22 OECD countries. Other recent studies have examined the ...

  Citation × Citation Citation Abstract Copy Title: The effects of population age on trade Author: Peterson, Zack T. This paper empirically examines the effects of population aging on international trade using a cross-country panel data set for a select group of 22 OECD countries. Other recent studies have examined the effects of population age on other economic variables such as growth, savings, and investment but none till now have considered age related effects on international trade. I use a simple linear empirical model to capture any age related effects on trade along with two different model specifications in this paper; one is a simple OLS and the other is a fixed effects linear trend adjusted OLS specification. The estimated results are then adjusted for heteroskedasticity and autocorrelation via the use of the Newey-West HAC estimator to account for problems common to cross-county panel data sets. I conclude that there is indeed, a positive and statistically significant (though not very robust relationship) between a country's population age and its export to GDP ratio. There are no statistically significant effects on other total trade, trade balance or import variables. Title: The effects of population age on trade Author: Peterson, Zack T. This paper empirically examines the effects of population aging on international trade using a cross-country panel data set for a select group of 22 OECD countries. Other recent studies have examined the effects of population age on other economic variables such as growth, savings, and investment but none till now have considered age related effects on international trade. I use a simple linear empirical model to capture any age related effects on trade along with two different model specifications in this paper; one is a simple OLS and the other is a fixed effects linear trend adjusted OLS specification. The estimated results are then adjusted for heteroskedasticity and autocorrelation via the use of the Newey-West HAC estimator to account for problems common to cross-county panel data sets. I conclude that there is indeed, a positive and statistically significant (though not very robust relationship) between a country's population age and its export to GDP ratio. There are no statistically significant effects on other total trade, trade balance or import variables. Close

• 44. [Article] Do Older Parents have More Self-Regulated Children?

  Strong self-regulation in early childhood is a key predictor of academic and social success from elementary school through college (McClelland et al., 2012). This study analyzed the influence of the age ...

  Citation × Citation Citation Abstract Copy Title: Do Older Parents have More Self-Regulated Children? Author: McClelland, Megan M., Harper, Kevin G. Strong self-regulation in early childhood is a key predictor of academic and social success from elementary school through college (McClelland et al., 2012). This study analyzed the influence of the age of the child’s parent on the child’s self-regulation as measured by the HTKS (Head-Toes-Knees-Shoulders) measure. Relations between children’s self-regulation scores and their parent’s age were initially examined and then were tested again after controlling for family income and child age. Higher child self-regulation was significantly related to having older parents. However, this correlation lost significance after family income (Head Start status) and child age were controlled. These results suggest that although parent age and child self-regulation are significantly related, family income and child age are stronger predictors of children’s self-regulation. Title: Do Older Parents have More Self-Regulated Children? Author: McClelland, Megan M., Harper, Kevin G. Strong self-regulation in early childhood is a key predictor of academic and social success from elementary school through college (McClelland et al., 2012). This study analyzed the influence of the age of the child’s parent on the child’s self-regulation as measured by the HTKS (Head-Toes-Knees-Shoulders) measure. Relations between children’s self-regulation scores and their parent’s age were initially examined and then were tested again after controlling for family income and child age. Higher child self-regulation was significantly related to having older parents. However, this correlation lost significance after family income (Head Start status) and child age were controlled. These results suggest that although parent age and child self-regulation are significantly related, family income and child age are stronger predictors of children’s self-regulation. Close

• 45. [Article] Time use for household tasks performed by school-age children in two-parent, two-child Oregon families

  The purpose of this study was to investigate the household tasks that school-age children perform and the average amount of time spent performing those tasks. The sample included 219 children in 135 families taken ...

  Citation × Citation Citation Abstract Copy Title: Time use for household tasks performed by school-age children in two-parent, two-child Oregon families Author: Kennedy, Louise Claudia The purpose of this study was to investigate the household tasks that school-age children perform and the average amount of time spent performing those tasks. The sample included 219 children in 135 families taken from the Oregon sample of 210 families interviewed for the Northeast Regional Research Project 113: "An Interstate Urban/Rural Comparison of Families' Time Use." Families included in this study were limited to those composed of two parents and at least one school-age child, since time data were not gathered for children under six years of age. Eighty-four families had two school-age children and 51 families had one school-age child and one younger child under six years of age. There were 116 boys and 103 girls in the 66 rural and 69 urban families. A questionnaire had been used to collect information on demographic characteristics and household data. A time chart had been used to record the precategorized activities of the homemaker, spouse, and children over six years of age for two separate 24-hour periods. The demographic variables used in the data analysis included age-group of the child, sex of the child, age of the sibling, place of residence, whether the homemaker was gainfully employed or a fulltime homemaker, occupation of homemaker, occupation of spouse, educational level of homemaker, educational level of spouse, and family income level. The chi square test of independence was used to determine whether there were relationships between the tasks school-age children performed and the demographic variables. Children's contributions to household work were concentrated in food preparation, dishwashing, shopping, housecleaning, and maintenance of home, yard, car, and pets. Fewer than 28 percent of the children contributed to care and construction of clothing and household linens, physical and nonphysical care of family members, or management. Overall, the types of tasks children performed were dependent upon the age of the child and the age of his/her sibling. Children age twelve through seventeen and those with younger siblings over six were more likely to perform household tasks than other children. Of the 219 children included in the study, 206 children (94.1 percent) contributed to household work. The number of tasks performed by a child ranged from zero to seven for one day and from zero to ten for a two-day period. One-way analysis of variance was used to test for differences in the average amount of time spent on all tasks when respondents were grouped by selected independent variables. Two null hypotheses were rejected indicating that there was a significant difference in the average amount of time spent on household tasks by school-age children according to the age-group and the sex of the child. Children ages 15 through 17 spent significantly more time performing household tasks than children in other age groups, and girls spent significantly more time performing household tasks than boys. The amount of time children contributed to household work ranged from five minutes per day to over fourteen hours per day. The average time contributed to household tasks by children was slightly over 81 minutes per day. Title: Time use for household tasks performed by school-age children in two-parent, two-child Oregon families Author: Kennedy, Louise Claudia The purpose of this study was to investigate the household tasks that school-age children perform and the average amount of time spent performing those tasks. The sample included 219 children in 135 families taken from the Oregon sample of 210 families interviewed for the Northeast Regional Research Project 113: "An Interstate Urban/Rural Comparison of Families' Time Use." Families included in this study were limited to those composed of two parents and at least one school-age child, since time data were not gathered for children under six years of age. Eighty-four families had two school-age children and 51 families had one school-age child and one younger child under six years of age. There were 116 boys and 103 girls in the 66 rural and 69 urban families. A questionnaire had been used to collect information on demographic characteristics and household data. A time chart had been used to record the precategorized activities of the homemaker, spouse, and children over six years of age for two separate 24-hour periods. The demographic variables used in the data analysis included age-group of the child, sex of the child, age of the sibling, place of residence, whether the homemaker was gainfully employed or a fulltime homemaker, occupation of homemaker, occupation of spouse, educational level of homemaker, educational level of spouse, and family income level. The chi square test of independence was used to determine whether there were relationships between the tasks school-age children performed and the demographic variables. Children's contributions to household work were concentrated in food preparation, dishwashing, shopping, housecleaning, and maintenance of home, yard, car, and pets. Fewer than 28 percent of the children contributed to care and construction of clothing and household linens, physical and nonphysical care of family members, or management. Overall, the types of tasks children performed were dependent upon the age of the child and the age of his/her sibling. Children age twelve through seventeen and those with younger siblings over six were more likely to perform household tasks than other children. Of the 219 children included in the study, 206 children (94.1 percent) contributed to household work. The number of tasks performed by a child ranged from zero to seven for one day and from zero to ten for a two-day period. One-way analysis of variance was used to test for differences in the average amount of time spent on all tasks when respondents were grouped by selected independent variables. Two null hypotheses were rejected indicating that there was a significant difference in the average amount of time spent on household tasks by school-age children according to the age-group and the sex of the child. Children ages 15 through 17 spent significantly more time performing household tasks than children in other age groups, and girls spent significantly more time performing household tasks than boys. The amount of time children contributed to household work ranged from five minutes per day to over fourteen hours per day. The average time contributed to household tasks by children was slightly over 81 minutes per day. Close

• 46. [Article] Age-specific and lifetime reproductive success of known age Northern Spotted Owls on four study areas in Oregon and Washington

  Northern Spotted Owls (Strix occidentalis caurina) are a long-lived forest owl and range-wide declines in their numbers have resulted in the species being listed as threatened under the endangered species ...

  Citation × Citation Citation Abstract Copy Title: Age-specific and lifetime reproductive success of known age Northern Spotted Owls on four study areas in Oregon and Washington Author: Loschl, Peter J. Northern Spotted Owls (Strix occidentalis caurina) are a long-lived forest owl and range-wide declines in their numbers have resulted in the species being listed as threatened under the endangered species act. While many studies have been focused on population trends and reproductive performance of Spotted Owls from different age-classes, none have examined age related performance or lifetime reproductive success of individual owls. Using data from known age Spotted Owls on four long-term demography studies in Oregon and Washington, I conducted separate analyses to examine the functional relationship of age and reproductive success, measured as the number of young fledged (NYF), and to examine lifetime reproductive success. In my age-specific analysis, I used a mixed models approach to account for repeated measures on individual owls. I found that the standard 3-level age-class approach (1-year-old, 2-year-old, adult) often used in Spotted Owl research was a poor fit relative to curvilinear and threshold models that allowed for age-dependent variation beyond age 3. A quadratic age effect was more often supported for males, whereas a threshold effect indicating a linear increase in NYF from ages 1 to 4 was most supported in the analyses of female data. Females tended to achieve a maximum in reproductive performance at earlier ages than males, and there appeared to be a negative relationship between the age when a maximum in mean NYF was reached and overall fecundity, as reported in earlier studies. Temporal variability in numbers of young fledged at each age was best modeled with a categorical year variable as opposed to a cyclic biennial ("even-odd") year effect. Lifetime reproductive success of Spotted Owls, measured as the total numbers of fledglings and recruits produced by individuals, varied widely. For owls with relatively complete data, the number of lifetime fledglings ranged from 0 to 20 and the number of lifetime offspring that were observed as recruits within study areas ranged from 0 to 7. There was a significant positive relationship between the number of lifetime young fledged and the number that later recruited locally. Seventy five percent of females and 67% of males bred at least once. Whereas 17% of females and 16% of males produced 50% of the offspring fledged by each sex, only 9% of females and 7% of males produced 50% of the banded young that were later observed as recruits. Thirty nine percent of females and 30% of males produced no fledglings and 64% of females and 69% of males produced no local recruits. Thus while most owls fledged at least 1 offspring, most did not produce any fledglings that recruited locally during the study. Cumulative proportions of individual owls that first bred at different ages indicated that females tended to initiate their breeding at earlier ages than males. Whereas 36% of females bred first at ages 1 or 2, only 19% of males bred first before age 3. Of the owls that bred, 98% of females and 91% of males bred at least once by age 6. Compared to owls on the three Oregon study areas, owls on the Cle Elum Study Area in the eastern Cascades of Washington bred early (>50% by age 2), had higher mean numbers of fledglings (>1) at most ages, and had short mean lifespans (6 years). On the Oregon study areas, owls first bred at later ages (>50% at age ≥3), had lower mean numbers of fledglings (0.4–0.7) at most ages, and had longer mean lifespans (7–9 years). These patterns appear consistent with a compensatory relationship between reproduction and survival that was suggested in at least one previous study. Life history theory is also consistent with the idea that where lower and more variable non-juvenile survival occurs (as has been documented on Cle Elum), selection pressure for earlier breeding and greater offspring production at each attempt are to be expected. Nevertheless, it is unclear if local conditions such as prey abundance, harsh winter conditions, or predation pressure act proximately to influence reproduction and survival of Spotted Owls in these studies, or if the variability in patterns of age-specific reproductive success and components of lifetime reproduction on these study areas reflect adaptive life history responses among populations of Spotted Owls. It is likely that both plasticity and life history adaptations underlie the differences and patterns that were revealed, but tests of these hypotheses were beyond the scope of my study. Title: Age-specific and lifetime reproductive success of known age Northern Spotted Owls on four study areas in Oregon and Washington Author: Loschl, Peter J. Northern Spotted Owls (Strix occidentalis caurina) are a long-lived forest owl and range-wide declines in their numbers have resulted in the species being listed as threatened under the endangered species act. While many studies have been focused on population trends and reproductive performance of Spotted Owls from different age-classes, none have examined age related performance or lifetime reproductive success of individual owls. Using data from known age Spotted Owls on four long-term demography studies in Oregon and Washington, I conducted separate analyses to examine the functional relationship of age and reproductive success, measured as the number of young fledged (NYF), and to examine lifetime reproductive success. In my age-specific analysis, I used a mixed models approach to account for repeated measures on individual owls. I found that the standard 3-level age-class approach (1-year-old, 2-year-old, adult) often used in Spotted Owl research was a poor fit relative to curvilinear and threshold models that allowed for age-dependent variation beyond age 3. A quadratic age effect was more often supported for males, whereas a threshold effect indicating a linear increase in NYF from ages 1 to 4 was most supported in the analyses of female data. Females tended to achieve a maximum in reproductive performance at earlier ages than males, and there appeared to be a negative relationship between the age when a maximum in mean NYF was reached and overall fecundity, as reported in earlier studies. Temporal variability in numbers of young fledged at each age was best modeled with a categorical year variable as opposed to a cyclic biennial ("even-odd") year effect. Lifetime reproductive success of Spotted Owls, measured as the total numbers of fledglings and recruits produced by individuals, varied widely. For owls with relatively complete data, the number of lifetime fledglings ranged from 0 to 20 and the number of lifetime offspring that were observed as recruits within study areas ranged from 0 to 7. There was a significant positive relationship between the number of lifetime young fledged and the number that later recruited locally. Seventy five percent of females and 67% of males bred at least once. Whereas 17% of females and 16% of males produced 50% of the offspring fledged by each sex, only 9% of females and 7% of males produced 50% of the banded young that were later observed as recruits. Thirty nine percent of females and 30% of males produced no fledglings and 64% of females and 69% of males produced no local recruits. Thus while most owls fledged at least 1 offspring, most did not produce any fledglings that recruited locally during the study. Cumulative proportions of individual owls that first bred at different ages indicated that females tended to initiate their breeding at earlier ages than males. Whereas 36% of females bred first at ages 1 or 2, only 19% of males bred first before age 3. Of the owls that bred, 98% of females and 91% of males bred at least once by age 6. Compared to owls on the three Oregon study areas, owls on the Cle Elum Study Area in the eastern Cascades of Washington bred early (>50% by age 2), had higher mean numbers of fledglings (>1) at most ages, and had short mean lifespans (6 years). On the Oregon study areas, owls first bred at later ages (>50% at age ≥3), had lower mean numbers of fledglings (0.4–0.7) at most ages, and had longer mean lifespans (7–9 years). These patterns appear consistent with a compensatory relationship between reproduction and survival that was suggested in at least one previous study. Life history theory is also consistent with the idea that where lower and more variable non-juvenile survival occurs (as has been documented on Cle Elum), selection pressure for earlier breeding and greater offspring production at each attempt are to be expected. Nevertheless, it is unclear if local conditions such as prey abundance, harsh winter conditions, or predation pressure act proximately to influence reproduction and survival of Spotted Owls in these studies, or if the variability in patterns of age-specific reproductive success and components of lifetime reproduction on these study areas reflect adaptive life history responses among populations of Spotted Owls. It is likely that both plasticity and life history adaptations underlie the differences and patterns that were revealed, but tests of these hypotheses were beyond the scope of my study. Close

• 47. [Article] Chronological Age, Mental Age and Socioeconomic Status Variance in Expressive Preposition Acquisition of Young Children

  The present study was designed to determine the ages at which a sample of children between eighteen and forty-two months verbally and correctly express the fourteen prepositions known to be acquired by ...

  Citation × Citation Citation Abstract Copy Title: Chronological Age, Mental Age and Socioeconomic Status Variance in Expressive Preposition Acquisition of Young Children Author: Heckel, Arthur J. Year: 1975 The present study was designed to determine the ages at which a sample of children between eighteen and forty-two months verbally and correctly express the fourteen prepositions known to be acquired by age four, using the Revised Expressive Preposition Test (REPT). The REPT was administered to sixty children chosen from day care centers and private homes within the metropolitan area of Portland, Oregon. Therewas no preference as to the sex, intelligence of the child or socio- economic status of the child's family. A statistical analysis was performed to determine the correlation between HEPT scores and the child's chronological age, mental age and the socioeconomic status of the child's family. Results show that expressive prepositions tend to be acquired at different age levels. Each age group tended to use a progressively greater number of the prepositions. None of the eighteen month olds used any of the prepositions. Only one-fourth of the twenty-four month olds used any of the prepositions. Half or more of the thirty month olds expressed the prepositions "under," "on," "in" and "up." Half or more of the thirty-six month olds expressed the prepositions "out of," "at," "in" and "up," but not "under" and "on." Half or more of the forty-two month olds expressed the prepositions "to, II, "out of," "under," "around," "at," "of," "with" and "up." One hundred per cent of the forty-two month olds also used the prepositions "in" and "on." The prepositions which were never expressed by 50 per cent of any of the children were "behind," "across," "off" and "by." A statistical analysis of the data revealed a moderate correlation between the children's REPT scores and their chronological ages (.68). Correlation coefficients indicated a high correlation between the children's REFT scores and their combined chronological and mental ages (.82). The children's SES scores did not correlate with REPT scores (1 per cent) when considered together with chronological and mental ages. Title: Chronological Age, Mental Age and Socioeconomic Status Variance in Expressive Preposition Acquisition of Young Children Author: Heckel, Arthur J. Year: 1975 The present study was designed to determine the ages at which a sample of children between eighteen and forty-two months verbally and correctly express the fourteen prepositions known to be acquired by age four, using the Revised Expressive Preposition Test (REPT). The REPT was administered to sixty children chosen from day care centers and private homes within the metropolitan area of Portland, Oregon. Therewas no preference as to the sex, intelligence of the child or socio- economic status of the child's family. A statistical analysis was performed to determine the correlation between HEPT scores and the child's chronological age, mental age and the socioeconomic status of the child's family. Results show that expressive prepositions tend to be acquired at different age levels. Each age group tended to use a progressively greater number of the prepositions. None of the eighteen month olds used any of the prepositions. Only one-fourth of the twenty-four month olds used any of the prepositions. Half or more of the thirty month olds expressed the prepositions "under," "on," "in" and "up." Half or more of the thirty-six month olds expressed the prepositions "out of," "at," "in" and "up," but not "under" and "on." Half or more of the forty-two month olds expressed the prepositions "to, II, "out of," "under," "around," "at," "of," "with" and "up." One hundred per cent of the forty-two month olds also used the prepositions "in" and "on." The prepositions which were never expressed by 50 per cent of any of the children were "behind," "across," "off" and "by." A statistical analysis of the data revealed a moderate correlation between the children's REPT scores and their chronological ages (.68). Correlation coefficients indicated a high correlation between the children's REFT scores and their combined chronological and mental ages (.82). The children's SES scores did not correlate with REPT scores (1 per cent) when considered together with chronological and mental ages. Close

• 48. [Article] The Mediating Effects of LMX on the Relationship Between Supervisor and Employee Age Differences, Satisfaction, and Retirement Intentions

  Increasing age heterogeneity within organizations is pressing researchers to better understand the effects of a multigenerational workforce, teams, and dyads. In response to this, the present research ...

  Citation × Citation Citation Abstract Copy Title: The Mediating Effects of LMX on the Relationship Between Supervisor and Employee Age Differences, Satisfaction, and Retirement Intentions Author: Pytlovany, Amy Christine Year: 2016 Increasing age heterogeneity within organizations is pressing researchers to better understand the effects of a multigenerational workforce, teams, and dyads. In response to this, the present research aimed to investigate the effect of employee and supervisor age (in)congruence in relation to job and life satisfaction, as well as retirement intentions, all mediated by leader-member exchange (LMX), using a time-lagged design. Two different theoretical foundations were investigated. Based on the relational demography literature, better outcomes were expected to be associated with age similarity. Theories about implicit expectations relating age and social role guided hypotheses suggesting that beyond just similarity or difference, the direction of age differences would matter. Based on traditional social assumptions that age is associated with experience and wisdom, it was expected that work outcomes would be better when the supervisor was older than the employee, and worse when the supervisor was younger than the employee. Results did not support any of the proposed hypotheses, with the exception of the established relationship between LMX and job satisfaction. However, response surface graphs and polynomial regression results directed post hoc analyses which did reveal a main effect of supervisor age on LMX and an indirect effect of supervisor age on Time 2 job satisfaction through Time 1 LMX. Employees in this sample reported higher quality LMX when supervisors were younger, regardless of employee age, and in turn employees with younger supervisors reported higher job satisfaction. These results and the trends depicted by response surface graphs are discussed in relation to implications for research and practice. Title: The Mediating Effects of LMX on the Relationship Between Supervisor and Employee Age Differences, Satisfaction, and Retirement Intentions Author: Pytlovany, Amy Christine Year: 2016 Increasing age heterogeneity within organizations is pressing researchers to better understand the effects of a multigenerational workforce, teams, and dyads. In response to this, the present research aimed to investigate the effect of employee and supervisor age (in)congruence in relation to job and life satisfaction, as well as retirement intentions, all mediated by leader-member exchange (LMX), using a time-lagged design. Two different theoretical foundations were investigated. Based on the relational demography literature, better outcomes were expected to be associated with age similarity. Theories about implicit expectations relating age and social role guided hypotheses suggesting that beyond just similarity or difference, the direction of age differences would matter. Based on traditional social assumptions that age is associated with experience and wisdom, it was expected that work outcomes would be better when the supervisor was older than the employee, and worse when the supervisor was younger than the employee. Results did not support any of the proposed hypotheses, with the exception of the established relationship between LMX and job satisfaction. However, response surface graphs and polynomial regression results directed post hoc analyses which did reveal a main effect of supervisor age on LMX and an indirect effect of supervisor age on Time 2 job satisfaction through Time 1 LMX. Employees in this sample reported higher quality LMX when supervisors were younger, regardless of employee age, and in turn employees with younger supervisors reported higher job satisfaction. These results and the trends depicted by response surface graphs are discussed in relation to implications for research and practice. Close

• 49. [Article] The circadian clock gene period extends healthspan in aging Drosophila melanogaster

  There is increasing evidence that aging is affected by biological (circadian) clocks – the internal mechanisms that coordinate daily changes in gene expression, physiological functions and behavior with ...

  Citation × Citation Citation Abstract Copy Title: The circadian clock gene period extends healthspan in aging Drosophila melanogaster Author: Giebultowicz, Jadwiga M., Chow, Eileen, Rakshit, Kuntol, Kretzchmar, Doris, Krishnan, Natraj There is increasing evidence that aging is affected by biological (circadian) clocks – the internal mechanisms that coordinate daily changes in gene expression, physiological functions and behavior with external day/night cycles. Recent data suggest that disruption of the mammalian circadian clock results in accelerated aging and increased age‐related pathologies such as cancer; however, the links between loss of daily rhythms and aging are not understood. We sought to determine whether disruption of the circadian clock affects lifespan and healthspan in the model organism Drosophila melanogaster. We examined effects of a null mutation in the circadian clock gene period (per01) on the fly healthspan by challenging aging flies with short‐term oxidative stress (24h hyperoxia) and investigating their response in terms of mortality hazard, levels of oxidative damage, and functional senescence. Exposure to 24hhyperoxia during middle age significantly shortened the life expectancy in per01 but not in control flies. This homeostatic challenge also led to significantly higher accumulation of oxidative damage in per01 flies compared to controls. In addition, aging per01 flies showed accelerated functional decline, such as lower climbing ability and increased neuronal degeneration compared to age‐matched controls. Together, these data suggest that impaired stress defense pathways may contribute to accelerated aging in the per mutant. In addition, we show that the expression of per gene declines in old wild type flies, suggesting that the circadian regulatory network becomes impaired with age. Title: The circadian clock gene period extends healthspan in aging Drosophila melanogaster Author: Giebultowicz, Jadwiga M., Chow, Eileen, Rakshit, Kuntol, Kretzchmar, Doris, Krishnan, Natraj There is increasing evidence that aging is affected by biological (circadian) clocks – the internal mechanisms that coordinate daily changes in gene expression, physiological functions and behavior with external day/night cycles. Recent data suggest that disruption of the mammalian circadian clock results in accelerated aging and increased age‐related pathologies such as cancer; however, the links between loss of daily rhythms and aging are not understood. We sought to determine whether disruption of the circadian clock affects lifespan and healthspan in the model organism Drosophila melanogaster. We examined effects of a null mutation in the circadian clock gene period (per01) on the fly healthspan by challenging aging flies with short‐term oxidative stress (24h hyperoxia) and investigating their response in terms of mortality hazard, levels of oxidative damage, and functional senescence. Exposure to 24hhyperoxia during middle age significantly shortened the life expectancy in per01 but not in control flies. This homeostatic challenge also led to significantly higher accumulation of oxidative damage in per01 flies compared to controls. In addition, aging per01 flies showed accelerated functional decline, such as lower climbing ability and increased neuronal degeneration compared to age‐matched controls. Together, these data suggest that impaired stress defense pathways may contribute to accelerated aging in the per mutant. In addition, we show that the expression of per gene declines in old wild type flies, suggesting that the circadian regulatory network becomes impaired with age. Close

• 50. [Article] Development and morphology of juvenile western juniper (Juniperus occidentalis Hook.)

  Whole tree excavation of 41 western juniper (Juniperus occidentalis Hook.), ranging in age from 2 to 34 years old, was used to assess the development and structure of root systems, to determine biomass ...

  Citation × Citation Citation Abstract Copy Title: Development and morphology of juvenile western juniper (Juniperus occidentalis Hook.) Author: Kramer, Susanne Whole tree excavation of 41 western juniper (Juniperus occidentalis Hook.), ranging in age from 2 to 34 years old, was used to assess the development and structure of root systems, to determine biomass allocation patterns, and to develop mathematical relationships for estimating biomass and root system dimensions in seedling and young western juniper. Both aboveground and belowground developmental patterns, including structural components and vertical and horizontal root spread, were described relative to plant age. Tree age and height were evaluated as predictors of biomass, root length, and root system dimensions of juvenile western juniper. Seedling root systems consisted of a relatively short tap root and a few weak laterals. With advancing age, root systems expanded in depth and lateral spread. Maximum observed rooting depth and horizontal extension were 1.20 m and 5.70 m, respectively. Root biomass and length allocation shifted from tap to lateral roots with increasing plant age. Lateral root growth dominated in trees older than 10 years. The majority of lateral roots emerged from the tap root between 5 and 20 cm from the soil surface. The relative proportions of accumulated weight in shoot components changed with progressing age. Foliage biomass accounted for the largest fraction of total standing weight throughout the developmental period examined. Adult foliage was first initiated at 17 years of age. Structural tissue increased and dead biomass decreased in relative proportion as the trees grew. Western juniper root/shoot biomass ratios ranged from 0.50 to 1.75 and showed little correlation with age. Fine root/foliage ratios varied between 0.85 and 4.38, and exhibited a significant decline with age. Tree age and height were consistently strong predictors for biomass of root and shoot components, root system length, and extension. Coefficients of determination from regressions on log-log transformed data ranged from 0.70 to 0.92 for tree age and from 0.84 to 0.96 for tree height. Title: Development and morphology of juvenile western juniper (Juniperus occidentalis Hook.) Author: Kramer, Susanne Whole tree excavation of 41 western juniper (Juniperus occidentalis Hook.), ranging in age from 2 to 34 years old, was used to assess the development and structure of root systems, to determine biomass allocation patterns, and to develop mathematical relationships for estimating biomass and root system dimensions in seedling and young western juniper. Both aboveground and belowground developmental patterns, including structural components and vertical and horizontal root spread, were described relative to plant age. Tree age and height were evaluated as predictors of biomass, root length, and root system dimensions of juvenile western juniper. Seedling root systems consisted of a relatively short tap root and a few weak laterals. With advancing age, root systems expanded in depth and lateral spread. Maximum observed rooting depth and horizontal extension were 1.20 m and 5.70 m, respectively. Root biomass and length allocation shifted from tap to lateral roots with increasing plant age. Lateral root growth dominated in trees older than 10 years. The majority of lateral roots emerged from the tap root between 5 and 20 cm from the soil surface. The relative proportions of accumulated weight in shoot components changed with progressing age. Foliage biomass accounted for the largest fraction of total standing weight throughout the developmental period examined. Adult foliage was first initiated at 17 years of age. Structural tissue increased and dead biomass decreased in relative proportion as the trees grew. Western juniper root/shoot biomass ratios ranged from 0.50 to 1.75 and showed little correlation with age. Fine root/foliage ratios varied between 0.85 and 4.38, and exhibited a significant decline with age. Tree age and height were consistently strong predictors for biomass of root and shoot components, root system length, and extension. Coefficients of determination from regressions on log-log transformed data ranged from 0.70 to 0.92 for tree age and from 0.84 to 0.96 for tree height. Close