Legume-Rhizobium symbiosis results in root nodules where rhizobia fix atmospheric nitrogen into p... more Legume-Rhizobium symbiosis results in root nodules where rhizobia fix atmospheric nitrogen into plant usable forms in exchange for plant-derived carbohydrates. The development of these specialized root organs involves a set of carefully orchestrated plant hormone signalling. In particular, a spatio-temporal balance between auxin and cytokinin appears to be crucial for proper nodule development. We put together a construct that carried nuclear localized fluorescence sensors for auxin and cytokinin and used two photon induced fluorescence microscopy for concurrent quantitative 3-dimensional imaging to determine cellular level auxin and cytokinin outputs and ratios in root and nodule tissues of soybean. The use of nuclear localization signals on the markers and nuclei segmentation during image processing enabled accurate monitoring of outputs in 3D image volumes. The ratiometric method used here largely compensates for variations in individual outputs due to sample turbidity and scatte...
Emergency departments (EDs) rarely screen for older driving safety. The Trail-Making Test B (TMT-... more Emergency departments (EDs) rarely screen for older driving safety. The Trail-Making Test B (TMT-B) is a neuropsychological test that may predict ability to drive. We sought to examine the driving patterns of older ED patients and the feasibility of screening patients in the ED using the TMT-B. At a single ED at a tertiary care center, we administered the TMT-B and a survey of health status and driving habits to a convenience sample of adult (age 18 and older) ED patients. We excluded those with altered mentation, critical illness, or language barriers. The TMT-B, scored by the time of first attempt, requires connection of letters and numbers in sequence on paper, and a time > or = 180 s may suggest elevated driving risk. We compared time to complete the TMT-B among ED patients to published norms. Of 144 patients ages 18 to 95, 95 (72.2%) were current drivers, and 91.4 percent of drivers were able to complete the TMT-B; 47.1 percent of drivers were older (65+), and 88.8 percent of older drivers rated their ability as good or excellent. In multivariate logistic regression, neither TMT-B performance nor being older predicted a recent collision. The mean TMT-B completion time was 66.1 (SD = 36.3, median = 56) s among drivers under age 65 and 117.5 (SD = 79.2, median = 95) s among those 65 or older. Approximately 1.9 percent (95% CI: 0.04-10.2) of drivers under 65 and 14.0 percent (95% CI: 5.3-27.9%) of drivers 65 or older required 180 s or more for the TMT-B. Using unpaired T-tests, study TMT-B times were not significantly different from previously published norms except among 25- to 34-year-olds (79.2 versus 50.7 s; p < 0.05) and 80- to 84-year-olds (223.9 versus 146.8 s; p < 0.01). Many older ED patients drive, and relatively healthy ED patients are able to complete the TMT-B with results similar to standard nomograms. The TMT-B may prove useful as part of targeted driver screening programs in EDs.
The number of personal bankruptcies has increased dramatically since 1990, and a growing number o... more The number of personal bankruptcies has increased dramatically since 1990, and a growing number of filers are divorced. While previous research shows that divorce significantly increases the probability of bankruptcy, these studies assume divorce is exogenous. This study uses the Panel Study of Income Dynamics to investigate the relationship between divorce and bankruptcy. Single-equation probit results show that divorce significantly increases the probability of bankruptcy and bankruptcy significantly increases the probability of divorce. However, after controlling for endogeneity, the effect of divorce on bankruptcy and the effect of bankruptcy on divorce both fall by a significant amount and are statistically insignificant. The findings suggest that future research needs to more carefully model the role that financial distress plays within a marriage.
Neuronal calcium sensors (NCSs) belong to a family of Ca 2؉-binding proteins, which serve importa... more Neuronal calcium sensors (NCSs) belong to a family of Ca 2؉-binding proteins, which serve important functions in neurotransmission, and are highly conserved from yeast to humans. Overexpression of the neuronal calcium sensor-1, called frequenin in the fruit fly and in frog, increases the release of neurotransmitters. Studying the functional role of frequenin in mammals and understanding its structural dynamics is critically dependent on the availability of active purified protein. Neuronal calcium sensors like other members of the family share common structural features: they contain four EF-hands as potential binding sites for Ca 2؉ and an N-terminal consensus sequence for myristoylation. Previously, recoverin, distantly related to NCSs, has been expressed and purified from Escherichia coli, involving a combination of different chromatographic steps. NCS-1 has earlier been purified adopting a two-step procedure used for recoverin purification. We have overexpressed NCS-1 from rat in its myristoylated and nonmyristoylated form in E. coli and purified it from crude lysates using a single-step hydrophobic interaction chromatography. The purified protein was identified by Western blotting and mass spectrometry and assayed for its ability to bind Ca 2؉ using a Ca 2؉ shift assay, terbium fluorescence, and Stains-all binding. The present protocol provides a rapid, more efficient and simplified, single-step method for purifying NCS-1 for structural and functional studies. This method can also be applied to purify related proteins of the superfamily.
To assess whether resident physicians (MDs) could complete a death certificate for elderly patien... more To assess whether resident physicians (MDs) could complete a death certificate for elderly patients with injury-related fatalities and whether their abilities were related to training or other factors. SETTING: A large tertiary teaching hospital in Boston, Massachusetts. PARTICIPANTS: Three hundred thirty-six MDs. DESIGN: Through an anonymous Web-based test, MDs were questioned regarding prior training and experience in completion of death certificates. The MDs read a case of an elderly patient who died from intracranial bleeding after a fall and then completed a test death certificate. Whether proper completion was associated with MD characteristics such as year of residency, self-assessment, or previous death certificate experience was examined. RESULTS: Almost two-thirds (63.6%) of MDs completed the test. Of participants, 52% (95% confidence interval (CI) 5 46-59%) filled out the death certificate with the correct primary cause of death and 10% (95% CI 5 6-14%) listed the three major contributing causes of death. Only 35% (95% CI 5 28-41%) correctly reported injury as a contributing cause of death, but 51% of the participants reported a high level of confidence in their ability to complete a death certificate accurately. CONCLUSION: Accurate completion of the sample death certificate and identification of injury was low, and MDs overrated their abilities. Death certificates completed by MDs may not be accurate and may underestimate the contribution of injury to elderly mortality.
Previous work linking liquidity constraints to excessive consumption sensitivity have used househ... more Previous work linking liquidity constraints to excessive consumption sensitivity have used household level information on wealth and assets to split the sample into households that are likely to be constrained from those with access to credit and liquidity. In this paper, we use the sample splitting methods of previous authors but refine the criteria by using direct information on whether the household filed for bankruptcy in the last 10 years. Legally, a flag can appear on a bankruptcy filer’s credit report for up to 10 years after bankruptcy. This bankruptcy flag affects an individual’s credit score, and therefore the individual’s access to credit, which may make post-bankruptcy consumers liquidity constrained. Our results indicate that post-bankruptcy consumers exhibit excess sensitivity likely due to the bankruptcy flag. Consistency checks confirm that the source of sensitivity is due to liquidity constraints and not other observationally equivalent behavior.
Studies have shown that a growing number of divorced women were experiencing debt repayment probl... more Studies have shown that a growing number of divorced women were experiencing debt repayment problems during the 1980s. This study uses data from the Panel Study of Income Dynamics to (1) examine how debt repayment problems differ by marital status and gender and (2) investigate the role that supplemental income payments play in helping to mitigate repayment problems. The results show that divorced men and women are more likely to default on their debt obligations than married households. Further analysis reveals that increases in welfare payments significantly decrease the likelihood of default for divorced women but do not affect the probability of default for divorced men and married households. There is no evidence that payments related to child support and alimony affect default rates. The findings suggest that welfare benefits may help to mitigate the economic consequences of divorce for women. Loan delinquency and charge-off rates have been rising since 1990, and there has been a twofold increase in the number of personal bankruptcy filings (American Bankruptcy Institute 2005). Research indicates that the rise in household repayment problems has occurred at a significantly higher rate for divorced households than for married households (Sullivan and Warren 1999a, 1999b; Sullivan, Warren, and Westbrook 1995, 2000). The literature, which investigates the economic consequences of divorce, provides some plausible explanations (i.e.,
This paper examines inequality and mobility using measures of income and consumption. Consumption... more This paper examines inequality and mobility using measures of income and consumption. Consumption is claimed to be a better measure of permanent income and thus well-being, but most studies of inequality and mobility using U.S. data use income.This paper uses cohort data from the Consumer Expenditure Surveys on total consumption to impute consumption in the Panel Study of Income Dynamics. Then, we use this imputed consumption and actual income from the PSID to examine changes in inequality and mobility. Similar to earlier findings, we show that there has been a large increase in income inequality but no concurrent increase in consumption inequality in the 1990s. Conversely, income mobility and consumption mobility are similar during this time period.Finally, we link the concepts of inequality and mobility using a social welfare function. The results suggest that income mobility and consumption mobility more than offset the increases in inequality.
Legally, a bankruptcy flag can appear on an individual's credit report for up to ... more Legally, a bankruptcy flag can appear on an individual's credit report for up to 10 years after the filing. The flag affects an individual's credit score, and in turn, an individual's access to credit. In this article, we investigate how the bankruptcy flag affects access to credit along three dimensions–loan acceptance, the price of the loan as is determined by
ABSTRACT Spectroscopic imaging was used to study the surface plasmon polariton (SPP) enhanced upc... more ABSTRACT Spectroscopic imaging was used to study the surface plasmon polariton (SPP) enhanced upconversion luminescence of NaYF4:Tm:Yb nanoparticles embedded in PMMA supported on Au nanopillar arrays. Spatially-resolved upconversion spectra show enhancement in both the visible and near-infrared region of the spectrum, clearly associated with the plasmonic resonances of an engineered periodic array of nanopillars. The array has a lattice resonance associated with the SPP near 980nm, at the peak absorption of the Yb^3+ ion, while the local surface plasmon resonance (LSPR) of the individual pillars is seen to enhance the near-infrared emission of Tm^3+ near 800nm. The combined effect results in a significantly higher enhancement of the near-infrared emission when compared to the visible upconversion lines of Tm^3+, consistent with the interpretation of sequential surface plasmon assisted absorption and emission at two separate and disparate energies. The presence of SPP and LSPR were confirmed by spectrally resolved reflectivity, and the mechanism for luminescence enhancement was investigated by time resolved measurements of the luminescence decay. Reflectivity measurements are compared to finite difference time domain simulations (FDTD).
Recent studies have shown that food consumption declines at retirement. We use broader definition... more Recent studies have shown that food consumption declines at retirement. We use broader definitions of consumption from the Consumer Expenditure Survey and find that the so-called retirement consumption puzzle is solved by using comprehensive consumption ...
Legume-Rhizobium symbiosis results in root nodules where rhizobia fix atmospheric nitrogen into p... more Legume-Rhizobium symbiosis results in root nodules where rhizobia fix atmospheric nitrogen into plant usable forms in exchange for plant-derived carbohydrates. The development of these specialized root organs involves a set of carefully orchestrated plant hormone signalling. In particular, a spatio-temporal balance between auxin and cytokinin appears to be crucial for proper nodule development. We put together a construct that carried nuclear localized fluorescence sensors for auxin and cytokinin and used two photon induced fluorescence microscopy for concurrent quantitative 3-dimensional imaging to determine cellular level auxin and cytokinin outputs and ratios in root and nodule tissues of soybean. The use of nuclear localization signals on the markers and nuclei segmentation during image processing enabled accurate monitoring of outputs in 3D image volumes. The ratiometric method used here largely compensates for variations in individual outputs due to sample turbidity and scatte...
Emergency departments (EDs) rarely screen for older driving safety. The Trail-Making Test B (TMT-... more Emergency departments (EDs) rarely screen for older driving safety. The Trail-Making Test B (TMT-B) is a neuropsychological test that may predict ability to drive. We sought to examine the driving patterns of older ED patients and the feasibility of screening patients in the ED using the TMT-B. At a single ED at a tertiary care center, we administered the TMT-B and a survey of health status and driving habits to a convenience sample of adult (age 18 and older) ED patients. We excluded those with altered mentation, critical illness, or language barriers. The TMT-B, scored by the time of first attempt, requires connection of letters and numbers in sequence on paper, and a time > or = 180 s may suggest elevated driving risk. We compared time to complete the TMT-B among ED patients to published norms. Of 144 patients ages 18 to 95, 95 (72.2%) were current drivers, and 91.4 percent of drivers were able to complete the TMT-B; 47.1 percent of drivers were older (65+), and 88.8 percent of older drivers rated their ability as good or excellent. In multivariate logistic regression, neither TMT-B performance nor being older predicted a recent collision. The mean TMT-B completion time was 66.1 (SD = 36.3, median = 56) s among drivers under age 65 and 117.5 (SD = 79.2, median = 95) s among those 65 or older. Approximately 1.9 percent (95% CI: 0.04-10.2) of drivers under 65 and 14.0 percent (95% CI: 5.3-27.9%) of drivers 65 or older required 180 s or more for the TMT-B. Using unpaired T-tests, study TMT-B times were not significantly different from previously published norms except among 25- to 34-year-olds (79.2 versus 50.7 s; p < 0.05) and 80- to 84-year-olds (223.9 versus 146.8 s; p < 0.01). Many older ED patients drive, and relatively healthy ED patients are able to complete the TMT-B with results similar to standard nomograms. The TMT-B may prove useful as part of targeted driver screening programs in EDs.
The number of personal bankruptcies has increased dramatically since 1990, and a growing number o... more The number of personal bankruptcies has increased dramatically since 1990, and a growing number of filers are divorced. While previous research shows that divorce significantly increases the probability of bankruptcy, these studies assume divorce is exogenous. This study uses the Panel Study of Income Dynamics to investigate the relationship between divorce and bankruptcy. Single-equation probit results show that divorce significantly increases the probability of bankruptcy and bankruptcy significantly increases the probability of divorce. However, after controlling for endogeneity, the effect of divorce on bankruptcy and the effect of bankruptcy on divorce both fall by a significant amount and are statistically insignificant. The findings suggest that future research needs to more carefully model the role that financial distress plays within a marriage.
Neuronal calcium sensors (NCSs) belong to a family of Ca 2؉-binding proteins, which serve importa... more Neuronal calcium sensors (NCSs) belong to a family of Ca 2؉-binding proteins, which serve important functions in neurotransmission, and are highly conserved from yeast to humans. Overexpression of the neuronal calcium sensor-1, called frequenin in the fruit fly and in frog, increases the release of neurotransmitters. Studying the functional role of frequenin in mammals and understanding its structural dynamics is critically dependent on the availability of active purified protein. Neuronal calcium sensors like other members of the family share common structural features: they contain four EF-hands as potential binding sites for Ca 2؉ and an N-terminal consensus sequence for myristoylation. Previously, recoverin, distantly related to NCSs, has been expressed and purified from Escherichia coli, involving a combination of different chromatographic steps. NCS-1 has earlier been purified adopting a two-step procedure used for recoverin purification. We have overexpressed NCS-1 from rat in its myristoylated and nonmyristoylated form in E. coli and purified it from crude lysates using a single-step hydrophobic interaction chromatography. The purified protein was identified by Western blotting and mass spectrometry and assayed for its ability to bind Ca 2؉ using a Ca 2؉ shift assay, terbium fluorescence, and Stains-all binding. The present protocol provides a rapid, more efficient and simplified, single-step method for purifying NCS-1 for structural and functional studies. This method can also be applied to purify related proteins of the superfamily.
To assess whether resident physicians (MDs) could complete a death certificate for elderly patien... more To assess whether resident physicians (MDs) could complete a death certificate for elderly patients with injury-related fatalities and whether their abilities were related to training or other factors. SETTING: A large tertiary teaching hospital in Boston, Massachusetts. PARTICIPANTS: Three hundred thirty-six MDs. DESIGN: Through an anonymous Web-based test, MDs were questioned regarding prior training and experience in completion of death certificates. The MDs read a case of an elderly patient who died from intracranial bleeding after a fall and then completed a test death certificate. Whether proper completion was associated with MD characteristics such as year of residency, self-assessment, or previous death certificate experience was examined. RESULTS: Almost two-thirds (63.6%) of MDs completed the test. Of participants, 52% (95% confidence interval (CI) 5 46-59%) filled out the death certificate with the correct primary cause of death and 10% (95% CI 5 6-14%) listed the three major contributing causes of death. Only 35% (95% CI 5 28-41%) correctly reported injury as a contributing cause of death, but 51% of the participants reported a high level of confidence in their ability to complete a death certificate accurately. CONCLUSION: Accurate completion of the sample death certificate and identification of injury was low, and MDs overrated their abilities. Death certificates completed by MDs may not be accurate and may underestimate the contribution of injury to elderly mortality.
Previous work linking liquidity constraints to excessive consumption sensitivity have used househ... more Previous work linking liquidity constraints to excessive consumption sensitivity have used household level information on wealth and assets to split the sample into households that are likely to be constrained from those with access to credit and liquidity. In this paper, we use the sample splitting methods of previous authors but refine the criteria by using direct information on whether the household filed for bankruptcy in the last 10 years. Legally, a flag can appear on a bankruptcy filer’s credit report for up to 10 years after bankruptcy. This bankruptcy flag affects an individual’s credit score, and therefore the individual’s access to credit, which may make post-bankruptcy consumers liquidity constrained. Our results indicate that post-bankruptcy consumers exhibit excess sensitivity likely due to the bankruptcy flag. Consistency checks confirm that the source of sensitivity is due to liquidity constraints and not other observationally equivalent behavior.
Studies have shown that a growing number of divorced women were experiencing debt repayment probl... more Studies have shown that a growing number of divorced women were experiencing debt repayment problems during the 1980s. This study uses data from the Panel Study of Income Dynamics to (1) examine how debt repayment problems differ by marital status and gender and (2) investigate the role that supplemental income payments play in helping to mitigate repayment problems. The results show that divorced men and women are more likely to default on their debt obligations than married households. Further analysis reveals that increases in welfare payments significantly decrease the likelihood of default for divorced women but do not affect the probability of default for divorced men and married households. There is no evidence that payments related to child support and alimony affect default rates. The findings suggest that welfare benefits may help to mitigate the economic consequences of divorce for women. Loan delinquency and charge-off rates have been rising since 1990, and there has been a twofold increase in the number of personal bankruptcy filings (American Bankruptcy Institute 2005). Research indicates that the rise in household repayment problems has occurred at a significantly higher rate for divorced households than for married households (Sullivan and Warren 1999a, 1999b; Sullivan, Warren, and Westbrook 1995, 2000). The literature, which investigates the economic consequences of divorce, provides some plausible explanations (i.e.,
This paper examines inequality and mobility using measures of income and consumption. Consumption... more This paper examines inequality and mobility using measures of income and consumption. Consumption is claimed to be a better measure of permanent income and thus well-being, but most studies of inequality and mobility using U.S. data use income.This paper uses cohort data from the Consumer Expenditure Surveys on total consumption to impute consumption in the Panel Study of Income Dynamics. Then, we use this imputed consumption and actual income from the PSID to examine changes in inequality and mobility. Similar to earlier findings, we show that there has been a large increase in income inequality but no concurrent increase in consumption inequality in the 1990s. Conversely, income mobility and consumption mobility are similar during this time period.Finally, we link the concepts of inequality and mobility using a social welfare function. The results suggest that income mobility and consumption mobility more than offset the increases in inequality.
Legally, a bankruptcy flag can appear on an individual's credit report for up to ... more Legally, a bankruptcy flag can appear on an individual's credit report for up to 10 years after the filing. The flag affects an individual's credit score, and in turn, an individual's access to credit. In this article, we investigate how the bankruptcy flag affects access to credit along three dimensions–loan acceptance, the price of the loan as is determined by
ABSTRACT Spectroscopic imaging was used to study the surface plasmon polariton (SPP) enhanced upc... more ABSTRACT Spectroscopic imaging was used to study the surface plasmon polariton (SPP) enhanced upconversion luminescence of NaYF4:Tm:Yb nanoparticles embedded in PMMA supported on Au nanopillar arrays. Spatially-resolved upconversion spectra show enhancement in both the visible and near-infrared region of the spectrum, clearly associated with the plasmonic resonances of an engineered periodic array of nanopillars. The array has a lattice resonance associated with the SPP near 980nm, at the peak absorption of the Yb^3+ ion, while the local surface plasmon resonance (LSPR) of the individual pillars is seen to enhance the near-infrared emission of Tm^3+ near 800nm. The combined effect results in a significantly higher enhancement of the near-infrared emission when compared to the visible upconversion lines of Tm^3+, consistent with the interpretation of sequential surface plasmon assisted absorption and emission at two separate and disparate energies. The presence of SPP and LSPR were confirmed by spectrally resolved reflectivity, and the mechanism for luminescence enhancement was investigated by time resolved measurements of the luminescence decay. Reflectivity measurements are compared to finite difference time domain simulations (FDTD).
Recent studies have shown that food consumption declines at retirement. We use broader definition... more Recent studies have shown that food consumption declines at retirement. We use broader definitions of consumption from the Consumer Expenditure Survey and find that the so-called retirement consumption puzzle is solved by using comprehensive consumption ...
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