1,302 research outputs found
FMRI Clustering and False Positive Rates
Recently, Eklund et al. (2016) analyzed clustering methods in standard FMRI
packages: AFNI (which we maintain), FSL, and SPM [1]. They claimed: 1) false
positive rates (FPRs) in traditional approaches are greatly inflated,
questioning the validity of "countless published fMRI studies"; 2)
nonparametric methods produce valid, but slightly conservative, FPRs; 3) a
common flawed assumption is that the spatial autocorrelation function (ACF) of
FMRI noise is Gaussian-shaped; and 4) a 15-year-old bug in AFNI's 3dClustSim
significantly contributed to producing "particularly high" FPRs compared to
other software. We repeated simulations from [1] (Beijing-Zang data [2], see
[3]), and comment on each point briefly.Comment: 3 pages, 1 figure. A Letter accepted in PNA
An Evaluation of Fee Hunting as a Technique to Capitalize on the Value of Deer in Northern New York
To research selected aspects of deer resource dynamics that have been identified as key components in the redefinition and/or implementation of deer management strategic plans and programs in northern New York
XMM-Newton Archival Study of the ULX Population in Nearby Galaxies
We present the results of an archival XMM-Newton study of the bright X-ray
point sources (L_X > 10^38 erg/s) in 32 nearby galaxies. From our list of
approximately 100 point sources, we attempt to determine if there is a
low-state counterpart to the Ultraluminous X-ray (ULX) population, searching
for a soft-hard state dichotomy similar to that known for Galactic X-ray
binaries and testing the specific predictions of the IMBH hypothesis. To this
end, we searched for "low-state" objects, which we defined as objects within
our sample which had a spectrum well fit by a simple absorbed power law, and
"high-state" objects, which we defined as objects better fit by a combined
blackbody and a power law. Assuming that ``low-state'' objects accrete at
approximately 10% of the Eddington luminosity (Done & Gierlinski 2003) and that
"high-state" objects accrete near the Eddington luminosity we further divided
our sample of sources into low and high state ULX sources. We classify 16
sources as low-state ULXs and 26 objects as high-state ULXs. As in Galactic
black hole systems, the spectral indices, Gamma, of the low-state objects, as
well as the luminosities, tend to be lower than those of the high-state
objects. The observed range of blackbody temperatures for the high state is
0.1-1 keV, with the most luminous systems tending toward the lowest
temperatures. We therefore divide our high-state ULXs into candidate IMBHs
(with blackbody temperatures of approximately 0.1 keV) and candidate stellar
mass BHs (with blackbody temperatures of approximately 1.0 keV). A subset of
the candidate stellar mass BHs have spectra that are well-fit by a
Comptonization model, a property similar of Galactic BHs radiating in the
"very-high" state near the Eddington limit.Comment: 54 pages, submitted to ApJ (March 2005), accepted (May 2006); changes
to organization of pape
B cell rich meningeal inflammation associates with increased spinal cord pathology in multiple sclerosis
Increased inflammation in the cerebral meninges is associated with extensive subpial cortical grey matter pathology in the forebrain and a more severe disease course in a substantial proportion of secondary progressive multiple sclerosis (SPMS) cases. It is not known whether this relationship extends to spinal cord pathology. We assessed the contribution of meningeal and parenchymal immune infiltrates to spinal cord pathology in SPMS cases characterised by the presence (F+) or absence (F-) of lymphoid-like structures in the forebrain meninges. Transverse cryosections of cervical, thoracic and lumbar cord of 22 SPMS and 5 control cases were analysed for CD20+ B cells, CD4+ and CD8+ T cells, microglia/macrophages (IBA-1+), demyelination (myelin oligodendrocyte glycoprotein+) and axon density (neurofilament-H+). Lymphoid-like structures containing follicular dendritic cell networks and dividing B cells were seen in the spinal meninges of three out of 11 F+SPMS cases. CD4+ and CD20+ cell counts were increased in F+SPMS compared to F-SPMS and controls, whilst axon loss was greatest in motor and sensory tracts of the F+SPMS cases (p<0.01). The density of CD20+ B cells of the spinal leptomeninges correlated with: CD4+ T cells and total B and T cells of the meninges; with the density of white matter perivascular CD20+ and CD4+ lymphocytes (p<0.05); with white matter lesion area (p<0.05); and the extent of axon loss (p<0.05) in F+SPMS cases only. We show that the presence of lymphoid-like structures in the forebrain is associated with a profound spinal cord pathology, and local B cell rich meningeal inflammation associates with the extent of cord pathology. Our work supports a principal role for B cells in sustaining inflammation and tissue injury throughout the CNS in the progressive disease stage
Guidelines for Integrating Deer and Timber Management in northern New York
To research selected aspects of deer resource dynamics that have been identified as key components in the redefinition and/or implementation of deer management strategic plans and programs in northern New York
A global merged land-airsea surface temperature reconstruction based on historical observations (1880–1997
ABSTRACT A merged land air surface and sea-surface temperature reconstruction analysis is developed for monthly anomalies. The reconstruction is global and spatially complete. Reconstructed anomalies damp towards zero in regions with insufficient sampling. Error estimates account for the damping associated with sparse sampling, and also for bias uncertainty in both the land and sea observations. Averages of the reconstruction are similar to simple averages of the unanalyzed data for most of the analysis period. For the 19 th century, when sampling is most sparse and the error estimates are largest, the differences between the averaged reconstruction and the simple averages are largest. Sampling is always sparse poleward of 60Âş latitude, and historic reconstructions for the polar regions should be used with caution.
Evidence for Relativistic Outflows in Narrow-line Seyfert 1 Galaxies
We report the observation of features near 1 keV in the ASCA spectra from
three ``Narrow Line Seyfert 1'' (NLS1) galaxies. We interpret these as oxygen
absorption in a highly relativistic outflow. If interpreted as absorption
edges, the implied velocities are 0.2--0.3c, near the limit predicted by
``line-locking'' radiative acceleration. If instead interpreted as broad
absorption lines, the implied velocities are ~0.57c, interestingly near the
velocity of particles in the last stable orbit around a Kerr black hole,
although a physical interpretation of this is not obvious. The features are
reminiscent of the UV absorption lines seen in broad absorption line quasars
(BALQSOs), but with larger velocities, and we note the remarkable similarities
in the optical emission line and broad band properties of NLS1s and
low-ionization BALQSOs.Comment: 9 pages using (AASTeX) aaspp4.sty and 2 Postscript figures. Accepted
for publication in Astrophysical Journal Letter
Work in Progress: The WSU Model for Engineering Mathematics Education
This paper summarizes progress to date on the WSU model for engineering mathematics education, an NSF funded curriculum reform initiative at Wright State University. The WSU model seeks to increase student retention, motivation and success in engineering through application-driven, just-in-time engineering math instruction. The WSU approach involves the development of a novel freshman-level engineering mathematics course EGR 101, as well as a large-scale restructuring of the engineering curriculum. By removing traditional math prerequisites and moving core engineering courses earlier in the program, the WSU model shifts the traditional emphasis on math prerequisite requirements to an emphasis on engineering motivation for math, with a just-in-time structuring of the new math sequence. This paper summarizes the development to date of the WSU model for engineering mathematics education, including a preliminary assessment of student performance and perception during the initial implementation of EGR 101. In addition, an assessment of first-year retention results is anticipated in time for the conference
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Comparisons of Daily Sea Surface Temperature Analyses for 2007–08
Six different SST analyses are compared with each other and with buoy data for the period 2007–08. All analyses used different combinations of satellite data [for example, infrared Advanced Very High Resolution Radiometer (AVHRR) and microwave Advanced Microwave Scanning Radiometer (AMSR) instruments] with different algorithms, spatial resolution, etc. The analyses considered are the National Climatic Data Center (NCDC) AVHRR-only and AMSR+AVHRR, the Navy Coupled Ocean Data Assimilation (NCODA), the Remote Sensing Systems (RSS), the Real-Time Global High-Resolution (RTG-HR), and the Operational SST and Sea Ice Analysis (OSTIA); the spatial grid sizes were 1/4°, 1/4°, 1/9°, 1/11°, 1/12°, and 1/20°, respectively. In addition, all analyses except RSS used in situ data. Most analysis procedures and weighting functions differed. Thus, differences among analyses could be large in high-gradient and data-sparse regions. An example off the coast of South Carolina showed winter SST differences that exceeded 5°C.
To help quantify SST analysis differences, wavenumber spectra were computed at several locations. These results suggested that the RSS is much noisier and that the RTG-HR analysis is much smoother than the other analyses. Further comparisons made using collocated buoys showed that RSS was especially noisy in the tropics and that RTG-HR had winter biases near the Aleutians region during January and February 2007. The correlation results show that NCODA and, to a somewhat lesser extent, OSTIA are strongly tuned locally to buoy data. The results also show that grid spacing does not always correlate with analysis resolution.
The AVHRR-only analysis is useful for climate studies because it is the only daily SST analysis that extends back to September 1981. Furthermore, comparisons of the AVHRR-only analysis and the AMSR+AVHRR analysis show that AMSR data can degrade the combined AMSR and AVHRR resolution in cloud-free regions while AMSR otherwise improves the resolution. These results indicate that changes in satellite instruments over time can impact SST analysis resolution.Keywords: Ship observations, Boundary currents, Sea surface temperature, Buoy observations, Satellite observation
The X-ray Remnant of SN1987A
We present high resolution Chandra observations of the remnant of SN1987A in
the Large Magellanic Cloud. The high angular resolution of the Chandra X-ray
Observatory (CXO) permits us to resolve the X-ray remnant. We find that the
remnant is shell-like in morphology, with X-ray peaks associated with some of
the optical hot spots seen in HST images. The X-ray light curve has departed
from the linear flux increase observed by ROSAT, with a 0.5-2.0 keV luminosity
of 1.5 x 10^35 erg/s in January 2000. We set an upper limit of 2.3 x 10^34
ergs/s on the luminosity of any embedded central source (0.5 - 2 keV). We also
present a high resolution spectrum, showing that the X-ray emission is thermal
in origin and is dominated by highly ionized species of O, Ne, Mg, and Si.Comment: 16 pages, 3 figures, Accepted for publication in ApJ Letter
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