1,063 research outputs found
Orbital Solutions and Absolute Elements of the Short-Period Eclipsing Binary ES Librae
We have obtained new differential UBV photoelectric photometry and radial velocities of both components of the short-period eclipsing binary ES Lib. The system has a circular orbit with a period of 0.883040928 days and is seen at an inclination of 70.1°. With the Wilson-Devinney analysis program, we obtained a simultaneous solution of our photometric and spectroscopic observations that resulted in masses of M1 = 2.30 ± 0.03 M⊙ and M2 = 0.97 ± 0.01 M⊙ and the equal-volume radii of R1 = 2.69 ± 0.02 R⊙ and R2 = 1.83 ± 0.01 R⊙ for the primary and secondary, respectively. The secondary is oversized and overluminous for its mass. The effective temperatures of the primary and secondary are 8500 K (fixed) and 5774 ± 57 K, respectively. Despite the very large temperature difference, our photometric and spectroscopic data indicate that ES Lib is not semidetached but rather require it to be in an overcontact state, where both components exceed their critical Roche lobes. Given its nonthermal equilibrium state, if the overcontact solution correctly characterizes the system, the change from being semidetached to overcontact may have occurred recently. While the asymmetry of the light curves can be modeled well with a large, hot starspot or a large, cool one on the secondary component, we prefer the latter interpretation because cool spots are a typical feature on many contact binaries
Sex matters during adolescence: Testosterone-related cortical thickness maturation differs between boys and girls
Age-related changes in cortical thickness have been observed during adolescence, including thinning in frontal and parietal cortices, and thickening in the lateral temporal lobes. Studies have shown sex differences in hormone-related brain maturation when boys and girls are age-matched, however, because girls mature 1-2 years earlier than boys, these sex differences could be confounded by pubertal maturation. To address puberty effects directly, this study assessed sex differences in testosterone-related cortical maturation by studying 85 boys and girls in a narrow age range and matched on sexual maturity. We expected that testosterone-by-sex interactions on cortical thickness would be observed in brain regions known from the animal literature to be high in androgen receptors. We found sex differences in associations between circulating testosterone and thickness in left inferior parietal lobule, middle temporal gyrus, calcarine sulcus, and right lingual gyrus, all regions known to be high in androgen receptors. Visual areas increased with testosterone in boys, but decreased in girls. All other regions were more impacted by testosterone levels in girls than boys. The regional pattern of sex-by-testosterone interactions may have implications for understanding sex differences in behavior and adolescent-onset neuropsychiatric disorders. © 2012 Bramen et al
Tensor Regression with Applications in Neuroimaging Data Analysis
Classical regression methods treat covariates as a vector and estimate a
corresponding vector of regression coefficients. Modern applications in medical
imaging generate covariates of more complex form such as multidimensional
arrays (tensors). Traditional statistical and computational methods are proving
insufficient for analysis of these high-throughput data due to their ultrahigh
dimensionality as well as complex structure. In this article, we propose a new
family of tensor regression models that efficiently exploit the special
structure of tensor covariates. Under this framework, ultrahigh dimensionality
is reduced to a manageable level, resulting in efficient estimation and
prediction. A fast and highly scalable estimation algorithm is proposed for
maximum likelihood estimation and its associated asymptotic properties are
studied. Effectiveness of the new methods is demonstrated on both synthetic and
real MRI imaging data.Comment: 27 pages, 4 figure
Disclosure of Maternal HIV Status to Children: To Tell or Not To Tell . . . That Is the Question
HIV-infected mothers face the challenging decision of whether to disclose their serostatus to their children. From the perspective of both mother and child, we explored the process of disclosure, providing descriptive information and examining the relationships among disclosure, demographic variables, and child adjustment. Participants were 23 mothers and one of their noninfected children (9 to 16 years of age). Sixty-one percent of mothers disclosed. Consistent with previous research, disclosure was not related to child functioning. However, children sworn to secrecy demonstrated lower social competence and more externalizing problems. Differential disclosure, which occurred in one-third of the families, was associated with higher levels of depressive and anxiety symptoms. Finally, knowing more than mothers had themselves disclosed was related to child maladjustment across multiple domains. Clinical implications and the need for future research are considered
Increased ventral striatal volume in college-aged binge drinkers
BACKGROUND
Binge drinking is a serious public health issue associated with cognitive, physiological, and anatomical differences from healthy individuals. No studies, however, have reported subcortical grey matter differences in this population. To address this, we compared the grey matter volumes of college-age binge drinkers and healthy controls, focusing on the ventral striatum, hippocampus and amygdala.
METHOD
T1-weighted images of 19 binge drinkers and 19 healthy volunteers were analyzed using voxel-based morphometry. Structural data were also covaried with Alcohol Use Disorders Identification Test (AUDIT) scores. Cluster-extent threshold and small volume corrections were both used to analyze imaging data.
RESULTS
Binge drinkers had significantly larger ventral striatal grey matter volumes compared to controls. There were no between group differences in hippocampal or amygdalar volume. Ventral striatal, amygdalar, and hippocampal volumes were also negatively related to AUDIT scores across groups.
CONCLUSIONS
Our findings stand in contrast to the lower ventral striatal volume previously observed in more severe forms of alcohol use disorders, suggesting that college-age binge drinkers may represent a distinct population from those groups. These findings may instead represent early sequelae, compensatory effects of repeated binge and withdrawal, or an endophenotypic risk factor
Longitudinal Impact of Childhood Adversity on Early Adolescent Mental Health During the COVID-19 Pandemic in the ABCD Study Cohort: Does Race or Ethnicity Moderate Findings?
Background During the COVID-19 pandemic in the United States, mental health among youth has been negatively affected. Youth with a history of adverse childhood experiences (ACEs), as well as youth from minoritized racial-ethnic backgrounds, may be especially vulnerable to experiencing COVID-19–related distress. The aims of this study are to examine whether exposure to pre-pandemic ACEs predicts mental health during the COVID-19 pandemic in youth and whether racial-ethnic background moderates these effects. Methods From May to August 2020, 7983 youths (mean age, 12.5 years; range, 10.6–14.6 years) in the Adolescent Brain Cognitive Development (ABCD) Study completed at least one of three online surveys measuring the impact of the pandemic on their mental health. Data were evaluated in relation to youths\u27 pre-pandemic mental health and ACEs. Results Pre-pandemic ACE history significantly predicted poorer mental health across all outcomes and greater COVID-19–related stress and impact of fears on well-being. Youths reported improved mental health during the pandemic (from May to August 2020). While reporting similar levels of mental health, youths from minoritized racial-ethnic backgrounds had elevated COVID-19–related worry, stress, and impact on well-being. Race and ethnicity generally did not moderate ACE effects. Older youths, girls, and those with greater pre-pandemic internalizing symptoms also reported greater mental health symptoms. Conclusions Youths who experienced greater childhood adversity reported greater negative affect and COVID-19–related distress during the pandemic. Although they reported generally better mood, Asian American, Black, and multiracial youths reported greater COVID-19–related distress and experienced COVID-19–related discrimination compared with non-Hispanic White youths, highlighting potential health disparities
Mathematical Manipulative Models: In Defense of Beanbag Biology
Mathematical manipulative models have had a long history of influence in biological research and in secondary school education, but they are frequently neglected in undergraduate biology education. By linking mathematical manipulative models in a four-step process-1) use of physical manipulatives, 2) interactive exploration of computer simulations, 3) derivation of mathematical relationships from core principles, and 4) analysis of real data sets-we demonstrate a process that we have shared in biological faculty development workshops led by staff from the BioQUEST Curriculum Consortium over the past 24 yr. We built this approach based upon a broad survey of literature in mathematical educational research that has convincingly demonstrated the utility of multiple models that involve physical, kinesthetic learning to actual data and interactive simulations. Two projects that use this approach are introduced: The Biological Excel Simulations and Tools in Exploratory, Experiential Mathematics (ESTEEM) Project (http://bioquest.org/esteem) and Numerical Undergraduate Mathematical Biology Education (NUMB3R5 COUNT; http://bioquest.org/numberscount). Examples here emphasize genetics, ecology, population biology, photosynthesis, cancer, and epidemiology. Mathematical manipulative models help learners break through prior fears to develop an appreciation for how mathematical reasoning informs problem solving, inference, and precise communication in biology and enhance the diversity of quantitative biology education
Age-related delay in information accrual for faces: Evidence from a parametric, single-trial EEG approach
Background: In this study, we quantified age-related changes in the time-course of face processing
by means of an innovative single-trial ERP approach. Unlike analyses used in previous studies, our
approach does not rely on peak measurements and can provide a more sensitive measure of
processing delays. Young and old adults (mean ages 22 and 70 years) performed a non-speeded
discrimination task between two faces. The phase spectrum of these faces was manipulated
parametrically to create pictures that ranged between pure noise (0% phase information) and the
undistorted signal (100% phase information), with five intermediate steps.
Results: Behavioural 75% correct thresholds were on average lower, and maximum accuracy was
higher, in younger than older observers. ERPs from each subject were entered into a single-trial
general linear regression model to identify variations in neural activity statistically associated with
changes in image structure. The earliest age-related ERP differences occurred in the time window
of the N170. Older observers had a significantly stronger N170 in response to noise, but this age
difference decreased with increasing phase information. Overall, manipulating image phase
information had a greater effect on ERPs from younger observers, which was quantified using a
hierarchical modelling approach. Importantly, visual activity was modulated by the same stimulus
parameters in younger and older subjects. The fit of the model, indexed by R2, was computed at
multiple post-stimulus time points. The time-course of the R2 function showed a significantly slower
processing in older observers starting around 120 ms after stimulus onset. This age-related delay
increased over time to reach a maximum around 190 ms, at which latency younger observers had
around 50 ms time lead over older observers.
Conclusion: Using a component-free ERP analysis that provides a precise timing of the visual
system sensitivity to image structure, the current study demonstrates that older observers
accumulate face information more slowly than younger subjects. Additionally, the N170 appears to
be less face-sensitive in older observers
Impact of in utero exposure to EtOH on corpus callosum development and paw preference in rats: protective effects of silymarin
BACKGROUND: Using a rat model we have found that the bioflavonoid silymarin (SY) ameliorates some of the negative consequences of in utero exposure to ethanol (EtOH). In the current study our aim was to determine if laterality preference and corpus callosum development were altered in rat offspring whose mothers were provided with a concomitant administration of SY with EtOH throughout gestation. METHODS: We provided pregnant Fisher/344 rats with liquid diets containing 35% ethanol derived calories (EDC) throughout the gestational period. A silymarin/phospholipid compound containing 29.8% silybin was co administered with EtOH to a separate experimental group. We tested the offspring for laterality preference at age 12 weeks. After testing the rats were sacrificed and their brains perfused for later corpus callosum extraction. RESULTS: We observed incomplete development of the splenium in the EtOH-only offspring. Callosal development was complete in all other treatment groups. Rats from the EtOH-only group displayed a left paw preference; whereas control rats were evenly divided between right and left paw preference. Inexplicably both SY groups were largely right paw preferring. CONCLUSIONS: The addition of SY to the EtOH liquid diet did confer some ameliorative effects upon the developing fetal rat brain
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