120 research outputs found
Explorations, Vol. 4, No. 1
Articles include:
Cover: Old Yarmouth Light, 1960, Cape Forchu, Nova Scotia. By and from the collection of Edgar McKay.
The Borderlands Concept: a new look at U.S.-Canada relations, by Victor Konrad and Lauren McKensey
Fundy Tidal Power Project, by Gregory White
Canadian Poet: Ken Norris
Native American Life and Art: a celebration, November, 1986, by Lee-Ann Konrad
The Montreal Canadiens: a cultural institution, by James J. Herlan
U.S. and Canadian Executives: uses of formal and informal plans in top executive decision-making, by Kent Carter
Our Cover Artist: bits and pieces of one man\u27s Nova Scotia, by Edgar McKay The Canadian-American Center and the Canadian Collection of the Fogler Library, by Alice Stewart
Capitalist Development in the New England-Atlantic Provinces Region, by Robert H. Babcock
Atlantic Canadian Members of Parliament as Representatives, by Howard Cody
The Rower and the Pyramid: a tribute to Joe Walsh, by Edward D. Ives
The Canadian-American Center: exercise in excellence, by Rand Erb
Canadian and Maine Potatoes: a bushel of questions, by George K. Griner, Alan S. Kezis, and James D. Leiby
After 20: the Future of the Canadian-American Center, by Victor Konra
A high spatial resolution X-ray and H-alpha study of hot gas in the halos of star-forming disk galaxies. II. Quantifying supernova feedback
We investigate how the empirical properties of hot X-ray-emitting gas in a
sample of seven starburst and three normal edge-on spiral galaxies (a sample
which covers the full range of star-formation intensity found in disk galaxies)
correlate with the size, mass, star formation rate and star formation intensity
in the host galaxies. Intriguingly, the diffuse X-ray properties of the normal
spirals (both in their disks and halos) fall where extrapolation of the trends
from the starburst galaxies with superwinds would predict. We demonstrate that
the luminosity of diffuse X-ray emission in both disk and halo is directly
proportional to the rate of mechanical energy feedback from massive stars.
Nevertheless, with only three non-starburst normal spiral galaxies it is hard
to exclude an accretion-based origin for extra-planar diffuse X-ray emission
around normal star-forming galaxies. Larger galaxies have more extended
X-ray-emitting halos, but galaxy mass appears to play no role in determining
the properties of the disk or extra-planar X-ray emitting plasma. The
combination of these luminosity and size correlations leads to a correlation
between the surface brightness of the diffuse X-ray emission and the mean star
formation rate per unit area in the disk (L_FIR/D_25^2). We argue that the
crucial spatial region around a galaxy that controls whether gas in
starburst-driven superwinds will escape into the IGM is not the outer halo ~100
kpc from the host galaxy, but the inner few halo scale heights, within ~20 kpc
of the galaxy plane. Given the properties of the gaseous halos we observe,
superwind outflows from disk galaxies of mass M ~ 10^10 -- 10^11 Msun should
still eject some fraction of their material into the IGM. (abstract abridged)Comment: To appear in 2004 May 10 edition of ApJ. For slightly higher
resolution version, see http://proteus.pha.jhu.edu/~dks/dks_published.htm
A high spatial resolution X-ray and H-alpha study of hot gas in the halos of star-forming disk galaxies. I. Spatial and spectral properties of the diffuse X-ray emission
We present arcsecond resolution Chandra X-ray and ground-based optical
H-alpha imaging of a sample of ten edge-on star-forming disk galaxies (seven
starburst and three ``normal'' spiral galaxies), a sample which covers the full
range of star-formation intensity found in disk galaxies. We use the
unprecedented spatial resolution of the Chandra X-ray observatory to robustly
remove point sources, and hence obtain the X-ray properties of the diffuse
thermal emission alone. The X-ray observations are combined with
comparable-resolution H-alpha and R-band imaging, and presented as a mini-atlas
of images on a common spatial and surface brightness scale. The vertical
distribution of the halo-region X-ray surface brightness is best described as
an exponential, with the observed scale heights lying in the range H_eff = 2 --
4 kpc. The ACIS X-ray spectra of extra-planar emission from all these galaxies
can be fit with a common two-temperature spectral model with an enhanced
alpha-to-iron element ratio. This is consistent with the origin of the X-ray
emitting gas being either metal-enriched merged SN ejecta or shock-heated
ambient halo or disk material with moderate levels of metal depletion onto
dust. The thermal X-ray emission observed in the halos of the starburst
galaxies is either this pre-existing halo medium, which has been swept-up and
shock heated by the starburst-driven wind, or wind material compressed near the
walls of the outflow by reverse shocks within the wind. In either case the
X-ray emission provides us with a powerful probe of the properties of gaseous
halos around star-forming disk galaxies.Comment: To appear in April 2004 edition of ApJS. For high resolution version,
see http://proteus.pha.jhu.edu/~dks/ Accepted version, now has nuclear and
total diffuse emission fluxes and luminosities, a few other minor change
Constitutive expression of cathepsin K in the human intervertebral disc: new insight into disc extracellular matrix remodeling via cathepsin K and receptor activator of nuclear factor-κB ligand
Slower is not always better: Response-time evidence clarifies the limited role of miserly information processing in the Cognitive Reflection Test
We report a study examining the role of `cognitive miserliness' as a determinant of poor performance on the standard three-item Cognitive Reflection Test (CRT). The cognitive miserliness hypothesis proposes that people often respond incorrectly on CRT items because of an unwillingness to go beyond default, heuristic processing and invest time and effort in analytic, reflective processing. Our analysis (N = 391) focused on people's response times to CRT items to determine whether predicted associations are evident between miserly thinking and the generation of incorrect, intuitive answers. Evidence indicated only a weak correlation between CRT response times and accuracy. Item-level analyses also failed to demonstrate predicted response time differences between correct analytic and incorrect intuitive answers for two of the three CRT items. We question whether participants who give incorrect intuitive answers on the CRT can legitimately be termed cognitive misers and whether the three CRT items measure the same general construct
A Meta-analysis of Multiple Myeloma Risk Regions in African and European Ancestry Populations Identifies Putatively Functional Loci
Genome-wide association studies (GWAS) in European populations have identified genetic risk variants associated with multiple myeloma (MM)
Common Variants at 9p21 and 8q22 Are Associated with Increased Susceptibility to Optic Nerve Degeneration in Glaucoma
Optic nerve degeneration caused by glaucoma is a leading cause of blindness worldwide. Patients affected by the normal-pressure form of glaucoma are more likely to harbor risk alleles for glaucoma-related optic nerve disease. We have performed a meta-analysis of two independent genome-wide association studies for primary open angle glaucoma (POAG) followed by a normal-pressure glaucoma (NPG, defined by intraocular pressure (IOP) less than 22 mmHg) subgroup analysis. The single-nucleotide polymorphisms that showed the most significant associations were tested for association with a second form of glaucoma, exfoliation-syndrome glaucoma. The overall meta-analysis of the GLAUGEN and NEIGHBOR dataset results (3,146 cases and 3,487 controls) identified significant associations between two loci and POAG: the CDKN2BAS region on 9p21 (rs2157719 [G], OR = 0.69 [95%CI 0.63–0.75], p = 1.86×10−18), and the SIX1/SIX6 region on chromosome 14q23 (rs10483727 [A], OR = 1.32 [95%CI 1.21–1.43], p = 3.87×10−11). In sub-group analysis two loci were significantly associated with NPG: 9p21 containing the CDKN2BAS gene (rs2157719 [G], OR = 0.58 [95% CI 0.50–0.67], p = 1.17×10−12) and a probable regulatory region on 8q22 (rs284489 [G], OR = 0.62 [95% CI 0.53–0.72], p = 8.88×10−10). Both NPG loci were also nominally associated with a second type of glaucoma, exfoliation syndrome glaucoma (rs2157719 [G], OR = 0.59 [95% CI 0.41–0.87], p = 0.004 and rs284489 [G], OR = 0.76 [95% CI 0.54–1.06], p = 0.021), suggesting that these loci might contribute more generally to optic nerve degeneration in glaucoma. Because both loci influence transforming growth factor beta (TGF-beta) signaling, we performed a genomic pathway analysis that showed an association between the TGF-beta pathway and NPG (permuted p = 0.009). These results suggest that neuro-protective therapies targeting TGF-beta signaling could be effective for multiple forms of glaucoma
SARS-CoV-2 susceptibility and COVID-19 disease severity are associated with genetic variants affecting gene expression in a variety of tissues
Variability in SARS-CoV-2 susceptibility and COVID-19 disease severity between individuals is partly due to
genetic factors. Here, we identify 4 genomic loci with suggestive associations for SARS-CoV-2 susceptibility
and 19 for COVID-19 disease severity. Four of these 23 loci likely have an ethnicity-specific component.
Genome-wide association study (GWAS) signals in 11 loci colocalize with expression quantitative trait loci
(eQTLs) associated with the expression of 20 genes in 62 tissues/cell types (range: 1:43 tissues/gene),
including lung, brain, heart, muscle, and skin as well as the digestive system and immune system. We perform
genetic fine mapping to compute 99% credible SNP sets, which identify 10 GWAS loci that have eight or fewer
SNPs in the credible set, including three loci with one single likely causal SNP. Our study suggests that the
diverse symptoms and disease severity of COVID-19 observed between individuals is associated with variants across the genome, affecting gene expression levels in a wide variety of tissue types
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
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