The purpose of this study was to conduct a meta-analysis summarizing the effectiveness of brief, ... more The purpose of this study was to conduct a meta-analysis summarizing the effectiveness of brief, single-session interventions to reduce alcohol use among heavy drinking college students. A comprehensive literature search identified 73 studies comparing the effects of single-session brief alcohol intervention with treatment-as-usual or no-treatment control conditions on alcohol use among heavy drinking college students. Random-effects meta-analyses with robust variance estimates were used to synthesize 662 effect sizes, estimating the average overall effect of the interventions and the variability in effects across a range of moderators. An overall mean effect size of ḡ = 0.18, 95% CI [0.12, 0.24] indicated that, on average, single-session brief alcohol interventions significantly reduced alcohol use among heavy drinking college students relative to comparison conditions. There was minimal variability in effects associated with study method and quality, general study characteristics,...
Using data from the Early Childhood Longitudinal Study-Kindergarten Cohort, this study was design... more Using data from the Early Childhood Longitudinal Study-Kindergarten Cohort, this study was designed to investigate proportional representation, identification rates, and predictors of language-minority (LM) learners in special education using a nationally representative sample of kindergarten, first graders, and third graders. The findings indicate that although LM learners were underrepresented in special education in kindergarten and first grade, they were overrepresented in third grade across all disability categories. LM status, teacher ratings of language and literacy skills, and reading proficiency level were significant predictors of placement in special education. Kindergarten teacher ratings of language and literacy skills were highly predictive of subsequent placement in special education. The implications for developing a model of early identification, the response-to-intervention model in particular, for LM learners at risk for academic difficulties are discussed.
... 537 Psychological Essentialism and Cultural Variation: Children’s Beliefs about Aggression in... more ... 537 Psychological Essentialism and Cultural Variation: Children’s Beliefs about Aggression in the United States and South Africa ...
Since previous short-term bioassays of methylmercury (MeHg) indicated no morphological effects in... more Since previous short-term bioassays of methylmercury (MeHg) indicated no morphological effects in zebrafish (Danio rerio) after embryonic exposures below 20 microg/l MeHg, studies were done to determine whether embryonic exposure to MeHg at lower concentrations would induce behavioral effects. Newly fertilized embryos were exposed to 0, 5, 10 or 15 microg MeHg/l for selected exposure durations: single day, multiple day or continuous exposure from fertilization through hatching. Larvae were maintained in an essential salt solution after hatching. Spontaneous swimming performance and prey capture experiments were conducted. Continuous embryonic exposure to 15 microg/l caused delayed mortality syndrome (DMS). These larvae hatched normally and appeared normal, but beginning at Day 3 post-hatch (ph), general activity was severely reduced and by Day 5 ph, larvae were completely moribund; many had faint heartbeats, severely enlarged body cavities and upward flexures of the spinal cord. Most of these larvae were dead by Day 6 ph. Multi- and single-day embryonic exposures to 15 microg/l caused reduced swimming activity and prey capture ability, and by Day 4 ph, these larvae also began to show signs of DMS. Continuous embryonic exposure to 10 microg/l significantly reduced spontaneous swimming activity, which did not improve after 5 days in clean water. Similar results were seen in larvae exposed during the last 24 h of embryonic development. Prey capture ability was also impaired in larvae exposed continuously to 10 microg/l, even after 4 days in clean water. Single-day exposures to 10 microg/l did not affect prey capture ability. Larvae from the 5-microg/l exposures were not significantly different from controls for either parameter. This study reinforces the idea that functional impairment is a more subtle response to developmental toxicants than mortality or the production of morphological defects.
Chronic bioassays were used to evaluate the concentration and exposure duration of methylmercury ... more Chronic bioassays were used to evaluate the concentration and exposure duration of methylmercury that resulted in specific teratogenic defects in Danio rerio embryos exposed at different developmental stages. Embryos in different stages of development (cleavage, blastula, gastrula, or segmentation) were exposed to 20 or 30 µg/l of methylmercuric chloride (CH(3)HgCl) for various exposure durations (8, 16, 32 h, or continuously to hatching). These exposures frequently caused two morphological defects, tissue abnormality in the median finfold and a flexure of the posterior tail region. The critical period of exposure for the production of both effects begins around 18-20 h after fertilization, with increased exposure resulting in more severe effects. These critical periods coincide with both tail and median finfold formation.
The purpose of this study was to conduct a meta-analysis summarizing the effectiveness of brief, ... more The purpose of this study was to conduct a meta-analysis summarizing the effectiveness of brief, single-session interventions to reduce alcohol use among heavy drinking college students. A comprehensive literature search identified 73 studies comparing the effects of single-session brief alcohol intervention with treatment-as-usual or no-treatment control conditions on alcohol use among heavy drinking college students. Random-effects meta-analyses with robust variance estimates were used to synthesize 662 effect sizes, estimating the average overall effect of the interventions and the variability in effects across a range of moderators. An overall mean effect size of ḡ = 0.18, 95% CI [0.12, 0.24] indicated that, on average, single-session brief alcohol interventions significantly reduced alcohol use among heavy drinking college students relative to comparison conditions. There was minimal variability in effects associated with study method and quality, general study characteristics,...
Using data from the Early Childhood Longitudinal Study-Kindergarten Cohort, this study was design... more Using data from the Early Childhood Longitudinal Study-Kindergarten Cohort, this study was designed to investigate proportional representation, identification rates, and predictors of language-minority (LM) learners in special education using a nationally representative sample of kindergarten, first graders, and third graders. The findings indicate that although LM learners were underrepresented in special education in kindergarten and first grade, they were overrepresented in third grade across all disability categories. LM status, teacher ratings of language and literacy skills, and reading proficiency level were significant predictors of placement in special education. Kindergarten teacher ratings of language and literacy skills were highly predictive of subsequent placement in special education. The implications for developing a model of early identification, the response-to-intervention model in particular, for LM learners at risk for academic difficulties are discussed.
... 537 Psychological Essentialism and Cultural Variation: Children’s Beliefs about Aggression in... more ... 537 Psychological Essentialism and Cultural Variation: Children’s Beliefs about Aggression in the United States and South Africa ...
Since previous short-term bioassays of methylmercury (MeHg) indicated no morphological effects in... more Since previous short-term bioassays of methylmercury (MeHg) indicated no morphological effects in zebrafish (Danio rerio) after embryonic exposures below 20 microg/l MeHg, studies were done to determine whether embryonic exposure to MeHg at lower concentrations would induce behavioral effects. Newly fertilized embryos were exposed to 0, 5, 10 or 15 microg MeHg/l for selected exposure durations: single day, multiple day or continuous exposure from fertilization through hatching. Larvae were maintained in an essential salt solution after hatching. Spontaneous swimming performance and prey capture experiments were conducted. Continuous embryonic exposure to 15 microg/l caused delayed mortality syndrome (DMS). These larvae hatched normally and appeared normal, but beginning at Day 3 post-hatch (ph), general activity was severely reduced and by Day 5 ph, larvae were completely moribund; many had faint heartbeats, severely enlarged body cavities and upward flexures of the spinal cord. Most of these larvae were dead by Day 6 ph. Multi- and single-day embryonic exposures to 15 microg/l caused reduced swimming activity and prey capture ability, and by Day 4 ph, these larvae also began to show signs of DMS. Continuous embryonic exposure to 10 microg/l significantly reduced spontaneous swimming activity, which did not improve after 5 days in clean water. Similar results were seen in larvae exposed during the last 24 h of embryonic development. Prey capture ability was also impaired in larvae exposed continuously to 10 microg/l, even after 4 days in clean water. Single-day exposures to 10 microg/l did not affect prey capture ability. Larvae from the 5-microg/l exposures were not significantly different from controls for either parameter. This study reinforces the idea that functional impairment is a more subtle response to developmental toxicants than mortality or the production of morphological defects.
Chronic bioassays were used to evaluate the concentration and exposure duration of methylmercury ... more Chronic bioassays were used to evaluate the concentration and exposure duration of methylmercury that resulted in specific teratogenic defects in Danio rerio embryos exposed at different developmental stages. Embryos in different stages of development (cleavage, blastula, gastrula, or segmentation) were exposed to 20 or 30 µg/l of methylmercuric chloride (CH(3)HgCl) for various exposure durations (8, 16, 32 h, or continuously to hatching). These exposures frequently caused two morphological defects, tissue abnormality in the median finfold and a flexure of the posterior tail region. The critical period of exposure for the production of both effects begins around 18-20 h after fertilization, with increased exposure resulting in more severe effects. These critical periods coincide with both tail and median finfold formation.
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Papers by Jennifer C Samson