1,154 research outputs found
That\u27s IrrELEPHANT: Children\u27s Judgments of Relevant and Irrelevant Animal Observations
Abstract:
The ability to make judgments about different kinds of evidence is an important skill for learning about science. This study investigated if children recognize how helpful relevant and irrelevant information is for evaluating biological explanations, and whether their judgments change with age. Participants were 24 7- and 8-year-olds and 26 9- and 10-year-olds. Children heard a statement about an animal\u27s behavior. Then children heard an explanation for that behavior followed by 2 different observations. One observation was about the same animal but was irrelevant to the explanation. The other observation was about a different animal, but was relevant to the explanation. Children rated the helpfulness of each observation. Older children were less likely to rate the observations as helpful than younger children. More importantly, both age groups rated different animal-relevant observations as more helpful than the same animal-irrelevant. The findings suggest that when children are learning about science, they can differentiate between kinds of evidence regardless of the topic. However, they may still require assistance from educators in order to make more accurate judgments.https://ir.library.louisville.edu/uars/1008/thumbnail.jp
A Novel Method for Reducing the Effect of Tonic Muscle Activity on the Gamma Band of the Scalp EEG
Neural oscillations in the gamma band are of increasing interest, but separating them from myogenic electrical activity has proved difficult. A novel algorithm has been developed to reduce the effect of tonic scalp and neck muscle activity on the gamma band of the EEG. This uses mathematical modelling to fit individual muscle spikes and then subtracts them from the data. The method was applied to the detection of motor associated gamma in two separate groups of eight subjects using different sampling rates. A reproducible increase in high gamma (65â85 Hz) magnitude occurred immediately after the motor action in the left central area (p = 0.02 and p = 0.0002 for the two cohorts with individually optimized algorithm parameters, compared to p = 0.03 and p = 0.16 before correction). Whilst the magnitude of this event-related gamma synchronisation was not reduced by the application of the EMG reduction algorithm, the baseline left central gamma magnitude was significantly reduced by an average of 23 % with a faster sampling rate (p < 0.05). In comparison, at left and right temporo-parietal locations the gamma amplitude was reduced by 60 and 54 % respectively (p < 0.05). The reduction of EMG contamination by fitting and subtraction of individual spikes shows promise as a method of improving the signal to noise ratio of high frequency neural oscillations in scalp EEG
The Initial Configuration of Young Stellar Clusters: A K-band Number Counts Analysis of the Surface Density of Stars
We present an analysis of K-band stellar distributions for the young stellar
clusters GGD 12-15, IRAS 20050+2720, and NGC 7129. We find that the two deeply
embedded clusters, GGD 12-15 and IRAS 20050+2720, are not azimuthally symmetric
and show a high degree of structure which traces filamentary structure observed
in 850 micron emission maps. In contrast, the NGC 7129 cluster is circularly
symmetric, less dense, and anti-correlated to 850 micron emission, suggesting
recent gas expulsion and dynamical expansion have occured. We estimate stellar
volume densities from nearest neighbor distances, and discuss the impact of
these densities on the evolution of circumstellar disks and protostellar
envelopes in these regions.Comment: 44 pages, 26 figures, Accepted to ApJ. Changes include extinction
mapping, Monte Carlo field star modeling, and Nyquist sampled azimuthal
stellar distributions. A version with full resolution figures is available at
http://astro.pas.rochester.edu/~rguter/preprints/gutermuth_sd.tar.g
Are We Making Progress in Medical Education?
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75582/1/j.1525-1497.2006.00446.x.pd
Spitzer, Near-Infrared, and Submillimeter Imaging of the Relatively Sparse Young Cluster, Lynds 988e
We present {\it Spitzer} images of the relatively sparse, low luminosity
young cluster L988e, as well as complementary near-infrared (NIR) and
submillimeter images of the region. The cluster is asymmetric, with the western
region of the cluster embedded within the molecular cloud, and the slightly
less dense eastern region to the east of, and on the edge of, the molecular
cloud. With these data, as well as with extant H data of stars
primarily found in the eastern region of the cluster, and a molecular CO
gas emission map of the entire region, we investigate the distribution of
forming young stars with respect to the cloud material, concentrating
particularly on the differences and similarities between the exposed and
embedded regions of the cluster. We also compare star formation in this region
to that in denser, more luminous and more massive clusters already investigated
in our comprehensive multi-wavelength study of young clusters within 1 kpc of
the Sun.Comment: 21 pages, 6 tables, 13 figures. Full resolution figures at:
http://astro.pas.rochester.edu/~tom/Preprints/L988e.pd
The Bay Area Functional Performance Evaluation: Development and Standardization
The Bay Area Functional Performance Evaluation (BaFPE) was developed i
Islands of linkage in an ocean of pervasive recombination reveals two-speed evolution of human cytomegalovirus genomes
Human cytomegalovirus (HCMV) infects most of the population worldwide, persisting throughout the host's life in a latent state with periodic episodes of reactivation. While typically asymptomatic, HCMV can cause fatal disease among congenitally infected infants and immunocompromised patients. These clinical issues are compounded by the emergence of antiviral resistance and the absence of an effective vaccine, the development of which is likely complicated by the numerous immune evasins encoded by HCMV to counter the host's adaptive immune responses, a feature that facilitates frequent super-infections. Understanding the evolutionary dynamics of HCMV is essential for the development of effective new drugs and vaccines. By comparing viral genomes from uncultivated or low-passaged clinical samples of diverse origins, we observe evidence of frequent homologous recombination events, both recent and ancient, and no structure of HCMV genetic diversity at the whole-genome scale. Analysis of individual gene-scale loci reveals a striking dichotomy: while most of the genome is highly conserved, recombines essentially freely and has evolved under purifying selection, 21 genes display extreme diversity, structured into distinct genotypes that do not recombine with each other. Most of these hyper-variable genes encode glycoproteins involved in cell entry or escape of host immunity. Evidence that half of them have diverged through episodes of intense positive selection suggests that rapid evolution of hyper-variable loci is likely driven by interactions with host immunity. It appears that this process is enabled by recombination unlinking hyper-variable loci from strongly constrained neighboring sites. It is conceivable that viral mechanisms facilitating super-infection have evolved to promote recombination between diverged genotypes, allowing the virus to continuously diversify at key loci to escape immune detection, while maintaining a genome optimally adapted to its asymptomatic infectious lifecycle
Symbiotic starburst-black hole AGN -- I. Isothermal hydrodynamics of the mass-loaded ISM
Compelling evidence associates the nuclei of active galaxies and massive
starbursts. The symbiosis between a compact nuclear starburst stellar cluster
and a massive black hole can self-consistently explain the properties of active
nuclei. The young stellar cluster has a profound effect on the most important
observable properties of active galaxies through its gravity, and by mass
injection through stellar winds, supernovae and stellar collisions. Mass
injection generates a nuclear ISM which flows under gravitational and radiative
forces until it leaves the nucleus or is accreted onto the black hole or
accretion disc.
The radiative force exerted by the black hole--accretion disc radiation field
is not spherically symmetric. This results in complex flows in which regions of
inflow can coexist with high Mach number outflowing winds and hydrodynamic
jets. We present two-dimensional hydrodynamic models of such nISM flows, which
are highly complex and time variable. Shocked shells, jets and explosive
bubbles are produced, with bipolar winds driving out from the nucleus. Our
results graphically illustrate why broad emission line studies have
consistently failed to identify any simple, global flow geometry. The real
structure of the flows is _inevitably_ yet more complex.Comment: 51 pages, 85 postscript figures, Latex, using MNRAS macros, to be
published in MNRAS. Postscript will full resolution pictures and mpeg
simulations available via http://ast.leeds.ac.uk/~rjrw/agn.htm
The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125
We report on multi-wavelength observations, ranging from the X-ray to radio
wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic
observations reveal the presence of absorption lines due to O I, Si II, and C
IV, implying a likely redshift of z = 1.547. The well-sampled light curves, in
particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days,
corresponding to a jet opening angle of ~7.0 degrees, and implying an intrinsic
GRB energy in the 1 - 10,000 keV band of around E = (6.3 - 6.9)x 10^(51) erg
(based on the fluences measured by the gamma-ray detectors of the IPN network).
GRB 070125 is among the brightest afterglows observed to date. The spectral
energy distribution implies a host extinction of Av < 0.9 mag. Two
rebrightening episodes are observed, one with excellent time coverage, showing
an increase in flux of 56% in ~8000 seconds. The evolution of the afterglow
light curve is achromatic at all times. Late-time observations of the afterglow
do not show evidence for emission from an underlying host galaxy or supernova.
Any host galaxy would be subluminous, consistent with current GRB host-galaxy
samples. Evidence for strong Mg II absorption features is not found, which is
perhaps surprising in view of the relatively high redshift of this burst and
the high likelihood for such features along GRB-selected lines of sight.Comment: 50 pages, 9 figures, 5 tables Accepted to the Astrophysical Journa
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