2,303 research outputs found
A global multicohort study to map subcortical brain development and cognition in infancy and early childhood
The human brain grows quickly during infancy and early childhood, but factors influencing brain maturation in this period remain poorly understood. To address this gap, we harmonized data from eight diverse cohorts, creating one of the largest pediatric neuroimaging datasets to date focused on birth to 6 years of age. We mapped the developmental trajectory of intracranial and subcortical volumes in ∼2,000 children and studied how sociodemographic factors and adverse birth outcomes influence brain structure and cognition. The amygdala was the first subcortical volume to mature, whereas the thalamus exhibited protracted development. Males had larger brain volumes than females, and children born preterm or with low birthweight showed catch-up growth with age. Socioeconomic factors exerted region- and time-specific effects. Regarding cognition, males scored lower than females; preterm birth affected all developmental areas tested, and socioeconomic factors affected visual reception and receptive language. Brain-cognition correlations revealed region-specific associations
Lithium and Lithium Depletion in Halo Stars on Extreme Orbits
We have determined Li abundances in 55 metal-poor (3.6 < [Fe/H] < -0.7) stars
with extreme orbital kinematics. We find the Li abundance in the Li-plateau
stars and examine its decrease in low-temperature, low-mass stars. The Li
observations are primarily from the Keck I telescope with HIRES (spectral
resolution of ~48,000 and median signal-to-noise per pixel of 140). Abundances
or upper limits were determined for Li for all the stars with typical errors of
0.06 dex. Our 14 stars on the Li plateau give A(Li) = log N(Li)/N(H) + 12.00 of
2.215 +-0.110, consistent with earlier results. We find a dependence of the Li
abundance on metallicity as measured by [Fe/H] and the Fe-peak elements [Cr/H]
and [Ni/H], with a slope of ~0.18. We also find dependences of A(Li) with the
alpha elements, Mg, Ca, and Ti. For the n-capture element, Ba, the relation
between A(Li) and [Ba/H] has a shallower slope of 0.13; over a range of 2.6 dex
in [Ba/H], the Li abundance spans only a factor of two. We examined the
possible trends of A(Li) with the characteristics of the orbits of our halo
stars, but find no relationship with kinematic or dynamic properties. The stars
cooler than the Li plateau are separated into three metallicity subsets. The
decrease in A(Li) sets in at hotter temperatures at high metallicities than at
low metallicities; this is in the opposite sense of the predictions for Li
depletion from standard and non-standard models.Comment: 29 pages including 3 tables and 12 figures Accepted by The
Astrophysical Journal, for the 1 November 2005 issue, v. 63
Personality predictors of levels of forgiveness two and a half years after the transgression
The aim of the present study was to explore whether the domains and facets of the five-factor model of personality predicted motivational states for avoidance and revenge following a transgression at a second temporal point distant from the original transgression. A sample of 438 university students, who reported experiencing a serious transgression against them, completed measures of avoidance and revenge motivations around the transgression and five-factor personality domains and facets at time 1, and measures of avoidance and revenge motivations two and a half years later. The findings suggest that neuroticism, and specifically anger hostility, predicts revenge and avoidance motivation
Lattice dynamics and negative thermal expansion in the framework compound ZnNi(CN)4 with 2-D and 3-D local environments
ZnNi(CN)4 is a 3-D framework material consisting of two interpenetrating PtS-type networks in which tetrahedral [ZnN4] units are linked by square-planar [NiC4] units. Both the parent compounds, cubic Zn(CN)2 and layered Ni(CN)2, are known to exhibit 3-D and 2-D negative thermal expansion (NTE), respectively. Temperature-dependent inelastic neutron scattering (INS) measurements were performed on a powdered sample of ZnNi(CN)4 to probe phonon dynamics. The measurements were underpinned by ab-initio lattice dynamical calculations. Good agreement was found between the measured and calculated generalized phonon density-of-states, validating our theoretical model and indicating that it is a good representation of the dynamics of the structural units. The calculated linear thermal expansion coefficients are αa = -21.2 × 10-6 K-1 and αc = +14.6 × 10-6 K-1, leading to an overall volume expansion coefficient, αV of -26.95 × 10-6 K-1, pointing towards pronounced NTE behaviour. Analysis of the derived mode-Grüneisen parameters shows that the optic modes around 12 and 40 meV make a significant contribution to the NTE. These modes involve localised rotational motions of the [NiC4] and/or [ZnN4] rigid units, echoing what has previously been observed in Zn(CN)2 and Ni(CN)2. However, in ZnNi(CN)4, modes below 10 meV have the most negative Grüneisen parameters. Analysis of their eigenvectors reveals that a large transverse motion of the Ni atom in the direction perpendicular to its square-planar environment induces a distortion of the units. This mode is a consequence of the Ni atom being constrained only in two dimensions within a 3-D framework. Hence, although rigid-unit modes account for some of the NTE-driving phonons, the added degree of freedom compared with Zn(CN)2 results in modes with twisting motions, capable of inducing greater NTE
Directional cerebrospinal fluid movement between brain ventricles in larval zebrafish
Background
Cerebrospinal fluid (CSF) contained within the brain ventricles contacts neuroepithelial progenitor cells during brain development. Dynamic properties of CSF movement may limit locally produced factors to specific regions of the developing brain. However, there is no study of in vivo CSF dynamics between ventricles in the embryonic brain. We address CSF movement using the zebrafish larva, during the major period of developmental neurogenesis.
Methods
CSF movement was monitored at two stages of zebrafish development: early larva [pharyngula stage; 27–30 h post-fertilization (hpf)] and late larva (hatching period; 51–54 hpf) using photoactivatable Kaede protein to calculate average maximum CSF velocity between ventricles. Potential roles for heartbeat in early CSF movement were investigated using tnnt2a mutant fish (tnnt2a [superscript −/−]) and chemical [2,3 butanedione monoxime (BDM)] treatment. Cilia motility was monitored at these stages using the Tg(βact:Arl13b–GFP) transgenic fish line.
Results
In wild-type early larva there is net CSF movement from the telencephalon to the combined diencephalic/mesencephalic superventricle. This movement directionality reverses at late larval stage. CSF moves directionally from diencephalic to rhombencephalic ventricles at both stages examined, with minimal movement from rhombencephalon to diencephalon. Directional movement is partially dependent on heartbeat, as indicated in assays of tnnt2a [superscript −/−] fish and after BDM treatment. Brain cilia are immotile at the early larval stage.
Conclusion
These data demonstrate directional movement of the embryonic CSF in the zebrafish model during the major period of developmental neurogenesis. A key conclusion is that CSF moves preferentially from the diencephalic into the rhombencephalic ventricle. In addition, the direction of CSF movement between telencephalic and diencephalic ventricles reverses between the early and late larval stages. CSF movement is partially dependent on heartbeat. At early larval stage, the absence of motile cilia indicates that cilia likely do not direct CSF movement. These data suggest that CSF components may be compartmentalized and could contribute to specialization of the early brain. In addition, CSF movement may also provide directional mechanical signaling.National Science Foundation (U.S.) (IOS-1258087)Howard Hughes Medical Institute (MIT Biology Summer internship program)Balkin-Markell-Weinberg Postdoctoral Fellowshi
Beliefs around luck : confirming the empirical conceptualization of beliefs around luck and the development of the Darke and Freedman beliefs around luck scale
The current study developed a multi-dimensional measure of beliefs around luck. Two studies introduced the Darke and Freedman beliefs around luck scale where the scale showed a consistent 4 component model (beliefs in luck, rejection of luck, being lucky, and being unlucky) across two samples (n = 250; n = 145). The scales also show adequate reliability statistics and validity by ways of comparison with other measures of beliefs around luck, peer and family ratings and expected associations with measures of personality, individual difference and well-being variables
Floral Scent Composition and Fine-Scale Timing in Two Moth-Pollinated Hawaiian <i>Schiedea</i> (Caryophyllaceae)
Floral scent often intensifies during periods of pollinator activity, but the degree of this synchrony may vary among scent compounds depending on their function. Related plant species with the same pollinator may exhibit similar timing and composition of floral scent. We compared timing and composition of floral volatiles for two endemic Hawaiian plant species, Schiedea kaalae and S. hookeri (Caryophyllaceae). For S. kaalae, we also compared the daily timing of emission of floral volatiles to evening visits of their shared pollinator, an endemic Hawaiian moth (Pseudoschrankia brevipalpis; Erebidae). The identity and amount of floral volatiles were measured in the greenhouse during day and evening periods with dynamic headspace sampling and GC-MS (gas chromatography - mass spectrometry). The timing of emissions (daily rise, peak, and fall) was measured by sampling continuously for multiple days in a growth chamber with PTR-MS (proton transfer reaction mass spectrometry). Nearly all volatiles detected underwent strong daily cycles in emission. Timings of floral volatile emissions were similar for S. kaalae and S. hookeri, as expected for two species sharing the same pollinator. For S. kaalae, many volatiles known to attract moths, including several linalool oxides and 2-phenylacetaldehyde, peaked within 2 h of the peak visitation time of the moth which pollinates both species. Floral volatiles of both species that peaked in the evening were also emitted several hours before and after the brief window of pollinator activity. Few volatiles followed a daytime emission pattern, consistent with increased apparency to visitors only at night. The scent blends of the two species differed in their major components and were most distinct from each other in the evening. The qualitative difference in evening scent composition between the two Schiedea species may reflect their distinct evolutionary history and may indicate that the moth species uses several different floral cues to locate rewards
Screening for Gynecologic Conditions With Pelvic Examination US Preventive Services Task Force Recommendation Statement
IMPORTANCE Many conditions that can affect women\u27s health are often evaluated through pelvic examination. Although the pelvic examination is a common part of the physical examination, it is unclear whether performing screening pelvic examinations in asymptomatic women has a significant effect on disease morbidity and mortality. OBJECTIVE To issue a new US Preventive Services Task Force(USPSTF) recommendation on screening for gynecologic conditions with pelvic examination for conditions other than cervical cancer, gonorrhea, and chlamydia, for which the USPSTF has already made specific recommendations. EVIDENCE REVIEW The USPSTF reviewed the evidence on the accuracy, benefits, and potential harms of performing screening pelvic examinations in asymptomatic, nonpregnant adult women 18 years and older who are not at increased risk for any specific gynecologic condition. FINDINGS Overall, the USPSTF found inadequate evidence on screening pelvic examinations for the early detection and treatment of a range of gynecologic conditions in asymptomatic, nonpregnant adult women. CONCLUSIONS AND RECOMMENDATION The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of performing screening pelvic examinations in asymptomatic, nonpregnant adult women. (I statement) This statement does not apply to specific disorders for which the USPSTF already recommends screening (ie, screening for cervical cancer with a Papanicolaou smear, screening for gonorrhea and chlamydia)
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