Christiana Drake - Academia.edu (original) (raw)
Papers by Christiana Drake
British Journal of …, Jan 1, 2011
Objective: To assess the relationship of acculturation with physical activity and sedentary behav... more Objective: To assess the relationship of acculturation with physical activity and sedentary behaviours among Hispanic women in California. Design: Data from the 2005 California Women's Health Survey (CWHS) – a cross-sectional telephonic survey of health indicators and health-related behaviours and attitudes – were used. Setting: Using a random-digit dialling process, data were collected monthly from January to December 2005. Subjects: A total of 1298 women aged $18 years in California who self-identified as Hispanic. Results: Of the participants included in the analysis, 49 % were adherent to physical activity recommendations (with 150 min of weekly activity signifying adherence). There was no significant association between language acculturation and moderate or vigorous physical activity after controlling for potential confounders such as smoking, age and employment status. There was also no association between duration of residence in the USA and moderate or vigorous physical activity. Language acculturation was positively associated with television (TV) viewing, with highly acculturated women reporting more hours of TV viewing compared with women with an intermediate acculturation score (P 5 0?0001), and those with an intermediate score reporting more hours of TV viewing compared with those with a low score (P 5 0?003). This relationship persisted after inclusion of smoking, employment status, age and education in the model. Conclusions: Higher levels of language acculturation may be associated with increased sedentary behaviours because of the influence of US culture on those women who have assimilated to the culture. Acculturation is an important factor to be taken into account when designing health education interventions for the Hispanic female population.
International Journal of Epidemiology, 1995
Subjects in observational studies of exposure effects have not been randomized to exposure groups... more Subjects in observational studies of exposure effects have not been randomized to exposure groups and may therefore differ systematically with regard to variables related to exposure and/or outcome. To obtain unbiased estimates and tests of exposure effects one needs to adjust for these variables. A common method is adjustment via a parametric model incorporating all known prognostic variables. Rosenbaum and Rubin propose adjustment by the conditional exposure probability given a set of covariates which they call the propensity score. They show that, at any value of the propensity score, covariates are on average balanced between exposure groups. Thus matching on the propensity score leads to unbiased estimators and tests of exposure effect. However, the validity of the method depends on knowing the exposure probability. This quantity is usually not known in observational studies and needs to be estimated.
Biometrika, 1995
ABSTRACT In observational studies some confounders may be unknown and therefore omitted from the ... more ABSTRACT In observational studies some confounders may be unknown and therefore omitted from the analysis while others are adjusted for. Approximations to the functions defining the relationship between the parameters in the full and reduced models are proposed leading to asymptotic bias estimates. Numerical calculations for logistic and Poisson regression models show good agreement between asymptotic and simulation bias. A data set containing the relationship between low birth weight and smoking (Hosmer & Lemeshow, 1989) is used as an illustration.
Biometrics, 1993
Page 1. BIOMETRICS 49, 1231-1236 December 1993 Effects of Misspecification of the Propensity Scor... more Page 1. BIOMETRICS 49, 1231-1236 December 1993 Effects of Misspecification of the Propensity Score on Estimators of Treatment Effect Christiana Drake Division of Statistics, University of California, Davis, California 95616, USA ...
Biometrical Journal, 1993
ABSTRACT The power of the Mantel-Haenszel test for no treatment effect in the case of binary expo... more ABSTRACT The power of the Mantel-Haenszel test for no treatment effect in the case of binary exposure and response variates was examined through simulation studies when subclasses were formed on the basis of the true and estimated propensity scores and by direct stratification on two continuous covariates. The power of these tests was also compared to the score test in a misspecified logistic regression model. In general adjustment by the true propensity score was most likely to reject a false null hypothesis, the score test was more likely to reject a false null hypothesis than the Mantel-Haenszel test when adjustment is by the estimated propensity score or subclassification on the covariates. There was litte difference in the observed powers of the Mantel-Haenszel tests between adjustment by the estimated propensity score and subclassification on the covariates.
We assessed blue oak (Quercus douglasii) sapling recruitment and regeneration at 15 locations dis... more We assessed blue oak (Quercus douglasii) sapling recruitment and regeneration at 15 locations distributed throughout the range of blue oak. Overall, 15.3 percent of the 1500 plots surveyed contained blue oak saplings. Four locations had moderate numbers of saplings, and the remaining locations had few to no saplings. Seedling-origin saplings were far more common than stump-sprout saplings. Most saplings were
Common clinical findings associated with acute intestinal rupture include depression, sweating, r... more Common clinical findings associated with acute intestinal rupture include depression, sweating, reluctance to walk, tachycardia, fever, hemoconcentration with normoproteinemia, leukopenia, abnormal mucous membranes, elevated peritoneal fluid protein concentration, and abnormal peritoneal fluid color. Abdominal radiography and ultrasound can be useful diagnostic aids for identification of pneumoperitoneum associated with intestinal rupture.
Journal of Criminal Justice
Journal of the American Veterinary Medical Association, Jan 15, 1999
To identify breed, age, sex, physical findings, history, and outcome of treatment in horses and o... more To identify breed, age, sex, physical findings, history, and outcome of treatment in horses and other equids with enterolithiasis. Retrospective study. 900 equids with enterolithiasis. Medical records from equids with enterolithiasis admitted between 1973 and 1996 were reviewed. Data on signalment, history, physical examination and clinicopathologic findings, surgical findings, and outcome were compiled from records and from telephone interviews with owners. Sex and breed predilections were determined by comparison of the study population with the general hospital population of equids during the same time period. Equids with enterolithiasis represented 15.1% of patients admitted for treatment colic, and 27.5% of patients undergoing celiotomy for treatment of colic. Arabian and Arabian crosses, Morgans, American Saddlebreds, and donkeys were significantly overrepresented, and Thoroughbreds, Standardbreds, warmbloods, and stallions were significantly underrepresented in the study popu...
JAMA
Alendronate sodium reduces fracture risk in postmenopausal women who have vertebral fractures, bu... more Alendronate sodium reduces fracture risk in postmenopausal women who have vertebral fractures, but its effects on fracture risk have not been studied for women without vertebral fractures. To test the hypothesis that 4 years of alendronate would decrease the risk of clinical and vertebral fractures in women who have low bone mineral density (BMD) but no vertebral fractures. Randomized, blinded, placebo-controlled trial. Eleven community-based clinical research centers. Women aged 54 to 81 years with a femoral neck BMD of 0.68 g/cm2 or less (Hologic Inc, Waltham, Mass) but no vertebral fracture; 4432 were randomized to alendronate or placebo and 4272 (96%) completed outcome measurements at the final visit (an average of 4.2 years later). All participants reporting calcium intakes of 1000 mg/d or less received a supplement containing 500 mg of calcium and 250 IU of cholecalciferol. Subjects were randomly assigned to either placebo or 5 mg/d of alendronate sodium for 2 years followed b...
Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine, 1998
The aim of our study was to determine whether maternal hydration status prior to prenatal sonogra... more The aim of our study was to determine whether maternal hydration status prior to prenatal sonography affects fetal renal pelvic diameter. The renal pelvic diameters of fetuses from two different institutions were compared prospectively. At one institution 74 women were asked to drink 32 to 48 ounces of water prior to undergoing sonography (hydration group), whereas at the second institution, no specific hydration regimen was requested of 176 subjects. The inclusion criteria were as follows: greater than 15 weeks' gestation, otherwise normal obstetrical sonogram, normal amniotic fluid volume, and negative family history for renal disease. Renal pelvic diameter, degree of maternal bladder fullness, and gestational age were compared between the two groups using logistic regression analysis and log-linear analysis. A P value < 0.01 was considered significant. Bladder fullness in the two groups differed significantly (P < 0.001). Logistic regression analysis showed a very stron...
The Journal of trauma, 1998
To determine whether there is an association between criminal activity and preference for a parti... more To determine whether there is an association between criminal activity and preference for a particular class of handgun among young adults who purchase handguns legally. Historical cohort study. Subjects were 5,360 authorized purchasers of handguns in California in 1988 who were 21 to 25 years of age, divided into two groups: all eligible purchasers with a previous criminal history (n = 2,765), and a random sample of purchasers with no such history (n = 2,595). Handguns were classified as small and inexpensive or larger and expensive. Associations were assessed by relative risks adjusted for gender and race or ethnicity. Handgun purchasers with a previous criminal history were more likely than those without such a history to purchase a small, inexpensive handgun (relative risk (RR) = 1.28; 95% confidence interval (CI), 1.16-1.42). Among handgun purchasers with no previous criminal history, those who purchased a small, inexpensive handgun were more likely than purchasers of other han...
American journal of veterinary research, 1996
To investigate the relation between several racing speed history characteristics and risk of fata... more To investigate the relation between several racing speed history characteristics and risk of fatal skeletal injury (FSI) in racing Thoroughbreds. 64 Thoroughbreds euthanatized during a 9-month period in 1991 at a California racemeet because of a catastrophic fracture incurred while racing (cases), identified retrospectively. For each race in which an FSI occurred, 1 control horse was randomly selected from the noncatastrophically injured participants. Racing and officially timed workout histories were obtained for each horse. Several history characteristics were calculated to summarize racing career patterns and high-speed exercise schedules prior to date of injury and included age at first race, proportion of career spent laid up, average duration of laid up periods, average lifetime racing frequency, time from last lay up to date of injury, and total and rate of distance accumulated 1 to 6 months prior to date of injury. History characteristics associated with FSI were screened by...
American journal of veterinary research, 1996
To compare the strength of the sutured linea alba, in vitro, using 2 suture patterns. 12 clinical... more To compare the strength of the sutured linea alba, in vitro, using 2 suture patterns. 12 clinically normal llamas. 2 incisions in the linea alba of 12 llamas were closed with a simple continuous or inverted cruciate pattern, and tissue was harvested after 10 days. In 6 llamas the simple continuous line was intact; the inverted cruciate specimens contained 6 sutures. In 6 llamas, 1 knot was excised in the simple continuous pattern to simulate a failed line; the cruciate pattern contained 5 knots. Tissue sections were taken from cranial, between, and caudal to the linea alba incisions to compare fascial thickness. The sutured specimens were mounted in a mechanical testing system and tested to failure. A mixed-model ANOVA was used to evaluate the effects of suture pattern and incisional position on mechanical properties. Significant differences were not found between suture patterns or between location for yield force, failure force, or yield strain, whereas failure strain was lower fo...
Pediatrics, 1989
Community programs to reduce the toll from pedestrian injuries in childhood must include parents ... more Community programs to reduce the toll from pedestrian injuries in childhood must include parents as a key element. This study, consisting of a survey questionnaire, was undertaken to provide information concerning current parent attitudes and practices that could be used to guide prevention programs. The survey consisted of 2464 questionnaires from parents of children in grades kindergarten to four in a suburban school district. Although 94% of parents did not believe that 5- to 6-year-old children can reliably cross streets alone, one third of parents allowed kindergarten-aged children to cross residential streets alone and first-grade children to walk alone to school. The presence of speeding traffic or the lack of safe places to walk did not influence parents in limiting their children's crossings. Few (17%) parents believed that children should be taught not to cross alone; one half of parents, including 41% of parents of kindergarten-aged children believed that children sho...
American journal of diseases of children (1960), 1991
--Drowning and near-drowning in residential swimming pools are leading causes of morbidity and mo... more --Drowning and near-drowning in residential swimming pools are leading causes of morbidity and mortality for young children. We tested the hypothesis that the period immediately after a pool is acquired is a time of high risk for these events. This study was also designed to provide population-based data on swimming pool immersion events, regardless of severity. --We conducted a mail survey of a probability sample of Sacramento County, California, households with in-ground swimming pools in January 1988; 80% of eligible subjects responded. Onset of exposure to a pool was defined as the month in which (1) the responding household had a pool installed, or (2) the responding household first occupied a residence with a pool. Exposures began in 1959 through 1987. --The home swimming pool immersion event rate was 11 per 1000 pool-years. The rate per 1000 pool-years was higher for the first 6 months of exposure than thereafter (0 to 6 months, 44; 7 to 24 months, 14; greater than 24 months, seven), but 77% of events occurred outside the high-risk period. For households whose exposures began in 1984 through 1987, the immersion event rate was 51 per 1000 pool-years overall and 123 per 1000 pool-years for the first 6 months of pool exposure; these increases probably represent underreporting of earlier events. In this group, 48% of events occurred outside the high-risk period. The family swimming pool accounted for 91% of immersion events at the respondents' homes. --The residential swimming pool is an important hazard for pool-owning households. The first 6 months of exposure constitute a high-risk period, but many immersion events occur later. Pool drowning prevention programs may focus on newly acquired swimming pools and their owners but should be as broad as possible to maximize their effectiveness.
The Journal of Trauma: Injury, Infection, and Critical Care, 1998
Radiology, 1999
To determine the weighted average sensitivity of magnetic resonance (MR) imaging in the prospecti... more To determine the weighted average sensitivity of magnetic resonance (MR) imaging in the prospective detection of acute neck injury and to compare these findings with those of a comprehensive conventional radiographic assessment. Conventional radiography and MR imaging were performed in 199 patients presenting to a level 1 trauma center with suspected cervical spine injury. Weighted sensitivities and specificities were calculated, and a weighted average across eight vertebral levels from C1 to T1 was formed. Fourteen parameters indicative of acute injury were tabulated. Fifty-eight patients had 172 acute cervical injuries. MR imaging depicted 136 (79%) acute abnormalities and conventional radiography depicted 39 (23%). For assessment of acute fractures, MR images (weighted average sensitivity, 43%; CI: 21%, 66%) were comparable to conventional radiographs (weighted average sensitivity, 48%; CI: 30%, 65%). MR imaging was superior to conventional radiography in the evaluation of pre- or paravertebral hemorrhage or edema, anterior or posterior longitudinal ligament injury, traumatic disk herniation, cord edema, and cord compression. Cord injuries were associated with cervical spine spondylosis (P &amp;amp;amp;lt; .05), acute fracture (P &amp;amp;amp;lt; .001), and canal stenosis (P &amp;amp;amp;lt; .001). MR imaging is more accurate than radiography in the detection of a wide spectrum of neck injuries, and further study is warranted of its potential effect on medical decision making, clinical outcome, and cost-effectiveness.
Lecture Notes in Mechanical Engineering, 2014
ABSTRACT Periodically correlated (or cyclostationary) time series are becoming more and more popu... more ABSTRACT Periodically correlated (or cyclostationary) time series are becoming more and more popular in many areas (see Gardner et al. 2006). However, in many practical situations data that can be modeled with such time series is incomplete. Some preliminary results on that problem have been presented in a previous work by Drake et al. (2013) by the authors. In this chapter we propose a new ECM-type algorithm based on conditional likelihood and profile likelihood to extend estimation to the case when observations are missing completely at random.
British Journal of …, Jan 1, 2011
Objective: To assess the relationship of acculturation with physical activity and sedentary behav... more Objective: To assess the relationship of acculturation with physical activity and sedentary behaviours among Hispanic women in California. Design: Data from the 2005 California Women's Health Survey (CWHS) – a cross-sectional telephonic survey of health indicators and health-related behaviours and attitudes – were used. Setting: Using a random-digit dialling process, data were collected monthly from January to December 2005. Subjects: A total of 1298 women aged $18 years in California who self-identified as Hispanic. Results: Of the participants included in the analysis, 49 % were adherent to physical activity recommendations (with 150 min of weekly activity signifying adherence). There was no significant association between language acculturation and moderate or vigorous physical activity after controlling for potential confounders such as smoking, age and employment status. There was also no association between duration of residence in the USA and moderate or vigorous physical activity. Language acculturation was positively associated with television (TV) viewing, with highly acculturated women reporting more hours of TV viewing compared with women with an intermediate acculturation score (P 5 0?0001), and those with an intermediate score reporting more hours of TV viewing compared with those with a low score (P 5 0?003). This relationship persisted after inclusion of smoking, employment status, age and education in the model. Conclusions: Higher levels of language acculturation may be associated with increased sedentary behaviours because of the influence of US culture on those women who have assimilated to the culture. Acculturation is an important factor to be taken into account when designing health education interventions for the Hispanic female population.
International Journal of Epidemiology, 1995
Subjects in observational studies of exposure effects have not been randomized to exposure groups... more Subjects in observational studies of exposure effects have not been randomized to exposure groups and may therefore differ systematically with regard to variables related to exposure and/or outcome. To obtain unbiased estimates and tests of exposure effects one needs to adjust for these variables. A common method is adjustment via a parametric model incorporating all known prognostic variables. Rosenbaum and Rubin propose adjustment by the conditional exposure probability given a set of covariates which they call the propensity score. They show that, at any value of the propensity score, covariates are on average balanced between exposure groups. Thus matching on the propensity score leads to unbiased estimators and tests of exposure effect. However, the validity of the method depends on knowing the exposure probability. This quantity is usually not known in observational studies and needs to be estimated.
Biometrika, 1995
ABSTRACT In observational studies some confounders may be unknown and therefore omitted from the ... more ABSTRACT In observational studies some confounders may be unknown and therefore omitted from the analysis while others are adjusted for. Approximations to the functions defining the relationship between the parameters in the full and reduced models are proposed leading to asymptotic bias estimates. Numerical calculations for logistic and Poisson regression models show good agreement between asymptotic and simulation bias. A data set containing the relationship between low birth weight and smoking (Hosmer & Lemeshow, 1989) is used as an illustration.
Biometrics, 1993
Page 1. BIOMETRICS 49, 1231-1236 December 1993 Effects of Misspecification of the Propensity Scor... more Page 1. BIOMETRICS 49, 1231-1236 December 1993 Effects of Misspecification of the Propensity Score on Estimators of Treatment Effect Christiana Drake Division of Statistics, University of California, Davis, California 95616, USA ...
Biometrical Journal, 1993
ABSTRACT The power of the Mantel-Haenszel test for no treatment effect in the case of binary expo... more ABSTRACT The power of the Mantel-Haenszel test for no treatment effect in the case of binary exposure and response variates was examined through simulation studies when subclasses were formed on the basis of the true and estimated propensity scores and by direct stratification on two continuous covariates. The power of these tests was also compared to the score test in a misspecified logistic regression model. In general adjustment by the true propensity score was most likely to reject a false null hypothesis, the score test was more likely to reject a false null hypothesis than the Mantel-Haenszel test when adjustment is by the estimated propensity score or subclassification on the covariates. There was litte difference in the observed powers of the Mantel-Haenszel tests between adjustment by the estimated propensity score and subclassification on the covariates.
We assessed blue oak (Quercus douglasii) sapling recruitment and regeneration at 15 locations dis... more We assessed blue oak (Quercus douglasii) sapling recruitment and regeneration at 15 locations distributed throughout the range of blue oak. Overall, 15.3 percent of the 1500 plots surveyed contained blue oak saplings. Four locations had moderate numbers of saplings, and the remaining locations had few to no saplings. Seedling-origin saplings were far more common than stump-sprout saplings. Most saplings were
Common clinical findings associated with acute intestinal rupture include depression, sweating, r... more Common clinical findings associated with acute intestinal rupture include depression, sweating, reluctance to walk, tachycardia, fever, hemoconcentration with normoproteinemia, leukopenia, abnormal mucous membranes, elevated peritoneal fluid protein concentration, and abnormal peritoneal fluid color. Abdominal radiography and ultrasound can be useful diagnostic aids for identification of pneumoperitoneum associated with intestinal rupture.
Journal of Criminal Justice
Journal of the American Veterinary Medical Association, Jan 15, 1999
To identify breed, age, sex, physical findings, history, and outcome of treatment in horses and o... more To identify breed, age, sex, physical findings, history, and outcome of treatment in horses and other equids with enterolithiasis. Retrospective study. 900 equids with enterolithiasis. Medical records from equids with enterolithiasis admitted between 1973 and 1996 were reviewed. Data on signalment, history, physical examination and clinicopathologic findings, surgical findings, and outcome were compiled from records and from telephone interviews with owners. Sex and breed predilections were determined by comparison of the study population with the general hospital population of equids during the same time period. Equids with enterolithiasis represented 15.1% of patients admitted for treatment colic, and 27.5% of patients undergoing celiotomy for treatment of colic. Arabian and Arabian crosses, Morgans, American Saddlebreds, and donkeys were significantly overrepresented, and Thoroughbreds, Standardbreds, warmbloods, and stallions were significantly underrepresented in the study popu...
JAMA
Alendronate sodium reduces fracture risk in postmenopausal women who have vertebral fractures, bu... more Alendronate sodium reduces fracture risk in postmenopausal women who have vertebral fractures, but its effects on fracture risk have not been studied for women without vertebral fractures. To test the hypothesis that 4 years of alendronate would decrease the risk of clinical and vertebral fractures in women who have low bone mineral density (BMD) but no vertebral fractures. Randomized, blinded, placebo-controlled trial. Eleven community-based clinical research centers. Women aged 54 to 81 years with a femoral neck BMD of 0.68 g/cm2 or less (Hologic Inc, Waltham, Mass) but no vertebral fracture; 4432 were randomized to alendronate or placebo and 4272 (96%) completed outcome measurements at the final visit (an average of 4.2 years later). All participants reporting calcium intakes of 1000 mg/d or less received a supplement containing 500 mg of calcium and 250 IU of cholecalciferol. Subjects were randomly assigned to either placebo or 5 mg/d of alendronate sodium for 2 years followed b...
Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine, 1998
The aim of our study was to determine whether maternal hydration status prior to prenatal sonogra... more The aim of our study was to determine whether maternal hydration status prior to prenatal sonography affects fetal renal pelvic diameter. The renal pelvic diameters of fetuses from two different institutions were compared prospectively. At one institution 74 women were asked to drink 32 to 48 ounces of water prior to undergoing sonography (hydration group), whereas at the second institution, no specific hydration regimen was requested of 176 subjects. The inclusion criteria were as follows: greater than 15 weeks' gestation, otherwise normal obstetrical sonogram, normal amniotic fluid volume, and negative family history for renal disease. Renal pelvic diameter, degree of maternal bladder fullness, and gestational age were compared between the two groups using logistic regression analysis and log-linear analysis. A P value < 0.01 was considered significant. Bladder fullness in the two groups differed significantly (P < 0.001). Logistic regression analysis showed a very stron...
The Journal of trauma, 1998
To determine whether there is an association between criminal activity and preference for a parti... more To determine whether there is an association between criminal activity and preference for a particular class of handgun among young adults who purchase handguns legally. Historical cohort study. Subjects were 5,360 authorized purchasers of handguns in California in 1988 who were 21 to 25 years of age, divided into two groups: all eligible purchasers with a previous criminal history (n = 2,765), and a random sample of purchasers with no such history (n = 2,595). Handguns were classified as small and inexpensive or larger and expensive. Associations were assessed by relative risks adjusted for gender and race or ethnicity. Handgun purchasers with a previous criminal history were more likely than those without such a history to purchase a small, inexpensive handgun (relative risk (RR) = 1.28; 95% confidence interval (CI), 1.16-1.42). Among handgun purchasers with no previous criminal history, those who purchased a small, inexpensive handgun were more likely than purchasers of other han...
American journal of veterinary research, 1996
To investigate the relation between several racing speed history characteristics and risk of fata... more To investigate the relation between several racing speed history characteristics and risk of fatal skeletal injury (FSI) in racing Thoroughbreds. 64 Thoroughbreds euthanatized during a 9-month period in 1991 at a California racemeet because of a catastrophic fracture incurred while racing (cases), identified retrospectively. For each race in which an FSI occurred, 1 control horse was randomly selected from the noncatastrophically injured participants. Racing and officially timed workout histories were obtained for each horse. Several history characteristics were calculated to summarize racing career patterns and high-speed exercise schedules prior to date of injury and included age at first race, proportion of career spent laid up, average duration of laid up periods, average lifetime racing frequency, time from last lay up to date of injury, and total and rate of distance accumulated 1 to 6 months prior to date of injury. History characteristics associated with FSI were screened by...
American journal of veterinary research, 1996
To compare the strength of the sutured linea alba, in vitro, using 2 suture patterns. 12 clinical... more To compare the strength of the sutured linea alba, in vitro, using 2 suture patterns. 12 clinically normal llamas. 2 incisions in the linea alba of 12 llamas were closed with a simple continuous or inverted cruciate pattern, and tissue was harvested after 10 days. In 6 llamas the simple continuous line was intact; the inverted cruciate specimens contained 6 sutures. In 6 llamas, 1 knot was excised in the simple continuous pattern to simulate a failed line; the cruciate pattern contained 5 knots. Tissue sections were taken from cranial, between, and caudal to the linea alba incisions to compare fascial thickness. The sutured specimens were mounted in a mechanical testing system and tested to failure. A mixed-model ANOVA was used to evaluate the effects of suture pattern and incisional position on mechanical properties. Significant differences were not found between suture patterns or between location for yield force, failure force, or yield strain, whereas failure strain was lower fo...
Pediatrics, 1989
Community programs to reduce the toll from pedestrian injuries in childhood must include parents ... more Community programs to reduce the toll from pedestrian injuries in childhood must include parents as a key element. This study, consisting of a survey questionnaire, was undertaken to provide information concerning current parent attitudes and practices that could be used to guide prevention programs. The survey consisted of 2464 questionnaires from parents of children in grades kindergarten to four in a suburban school district. Although 94% of parents did not believe that 5- to 6-year-old children can reliably cross streets alone, one third of parents allowed kindergarten-aged children to cross residential streets alone and first-grade children to walk alone to school. The presence of speeding traffic or the lack of safe places to walk did not influence parents in limiting their children's crossings. Few (17%) parents believed that children should be taught not to cross alone; one half of parents, including 41% of parents of kindergarten-aged children believed that children sho...
American journal of diseases of children (1960), 1991
--Drowning and near-drowning in residential swimming pools are leading causes of morbidity and mo... more --Drowning and near-drowning in residential swimming pools are leading causes of morbidity and mortality for young children. We tested the hypothesis that the period immediately after a pool is acquired is a time of high risk for these events. This study was also designed to provide population-based data on swimming pool immersion events, regardless of severity. --We conducted a mail survey of a probability sample of Sacramento County, California, households with in-ground swimming pools in January 1988; 80% of eligible subjects responded. Onset of exposure to a pool was defined as the month in which (1) the responding household had a pool installed, or (2) the responding household first occupied a residence with a pool. Exposures began in 1959 through 1987. --The home swimming pool immersion event rate was 11 per 1000 pool-years. The rate per 1000 pool-years was higher for the first 6 months of exposure than thereafter (0 to 6 months, 44; 7 to 24 months, 14; greater than 24 months, seven), but 77% of events occurred outside the high-risk period. For households whose exposures began in 1984 through 1987, the immersion event rate was 51 per 1000 pool-years overall and 123 per 1000 pool-years for the first 6 months of pool exposure; these increases probably represent underreporting of earlier events. In this group, 48% of events occurred outside the high-risk period. The family swimming pool accounted for 91% of immersion events at the respondents' homes. --The residential swimming pool is an important hazard for pool-owning households. The first 6 months of exposure constitute a high-risk period, but many immersion events occur later. Pool drowning prevention programs may focus on newly acquired swimming pools and their owners but should be as broad as possible to maximize their effectiveness.
The Journal of Trauma: Injury, Infection, and Critical Care, 1998
Radiology, 1999
To determine the weighted average sensitivity of magnetic resonance (MR) imaging in the prospecti... more To determine the weighted average sensitivity of magnetic resonance (MR) imaging in the prospective detection of acute neck injury and to compare these findings with those of a comprehensive conventional radiographic assessment. Conventional radiography and MR imaging were performed in 199 patients presenting to a level 1 trauma center with suspected cervical spine injury. Weighted sensitivities and specificities were calculated, and a weighted average across eight vertebral levels from C1 to T1 was formed. Fourteen parameters indicative of acute injury were tabulated. Fifty-eight patients had 172 acute cervical injuries. MR imaging depicted 136 (79%) acute abnormalities and conventional radiography depicted 39 (23%). For assessment of acute fractures, MR images (weighted average sensitivity, 43%; CI: 21%, 66%) were comparable to conventional radiographs (weighted average sensitivity, 48%; CI: 30%, 65%). MR imaging was superior to conventional radiography in the evaluation of pre- or paravertebral hemorrhage or edema, anterior or posterior longitudinal ligament injury, traumatic disk herniation, cord edema, and cord compression. Cord injuries were associated with cervical spine spondylosis (P &amp;amp;amp;lt; .05), acute fracture (P &amp;amp;amp;lt; .001), and canal stenosis (P &amp;amp;amp;lt; .001). MR imaging is more accurate than radiography in the detection of a wide spectrum of neck injuries, and further study is warranted of its potential effect on medical decision making, clinical outcome, and cost-effectiveness.
Lecture Notes in Mechanical Engineering, 2014
ABSTRACT Periodically correlated (or cyclostationary) time series are becoming more and more popu... more ABSTRACT Periodically correlated (or cyclostationary) time series are becoming more and more popular in many areas (see Gardner et al. 2006). However, in many practical situations data that can be modeled with such time series is incomplete. Some preliminary results on that problem have been presented in a previous work by Drake et al. (2013) by the authors. In this chapter we propose a new ECM-type algorithm based on conditional likelihood and profile likelihood to extend estimation to the case when observations are missing completely at random.