1,159 research outputs found
Optimizing ISOCAM data processing using spatial redundancy
We present new data processing techniques that allow to correct the main
instrumental effects that degrade the images obtained by ISOCAM, the camera on
board the Infrared Space Observatory (ISO). Our techniques take advantage of
the fact that a position on the sky has been observed by several pixels at
different times. We use this information (1) to correct the long term variation
of the detector response, (2) to correct memory effects after glitches and
point sources, and (3) to refine the deglitching process. Our new method allows
the detection of faint extended emission with contrast smaller than 1% of the
zodiacal background. The data reduction corrects instrumental effects to the
point where the noise in the final map is dominated by the readout and the
photon noises. All raster ISOCAM observations can benefit from the data
processing described here. These techniques could also be applied to other
raster type observations (e.g. ISOPHOT or IRAC on SIRTF).Comment: 13 pages, 10 figures, to be published in Astronomy and Astrophysics
Supplement Serie
IRIS: A new generation of IRAS maps
The Infrared Astronomical Satellite (IRAS) had a tremendous impact on many
areas of modern astrophysics. In particular it revealed the ubiquity of
infrared cirrus that are a spectacular manifestation of the interstellar medium
complexity but also an important foreground for observational cosmology. With
the forthcoming Planck satellite there is a need for all-sky complementary data
sets with arcminute resolution that can bring informations on specific
foreground emissions that contaminate the Cosmic Microwave Background
radiation. With its 4 arcmin resolution matching perfectly the high-frequency
bands of Planck, IRAS is a natural data set to study the variations of dust
properties at all scales. But the latest version of the images delivered by the
IRAS team (the ISSA plates) suffer from calibration, zero level and striping
problems that can preclude its use, especially at 12 and 25 micron. In this
paper we present how we proceeded to solve each of these problems and enhance
significantly the general quality of the ISSA plates in the four bands (12, 25,
60 and 100 micron). This new generation of IRAS images, called IRIS, benefits
from a better zodiacal light subtraction, from a calibration and zero level
compatible with DIRBE, and from a better destriping. At 100 micron the IRIS
product is also a significant improvement from the Schlegel et al. (1998) maps.
IRIS keeps the full ISSA resolution, it includes well calibrated point sources
and the diffuse emission calibration at scales smaller than 1 degree was
corrected for the variation of the IRAS detector responsivity with scale and
brightness. The uncertainty on the IRIS calibration and zero level are
dominated by the uncertainty on the DIRBE calibration and on the accuracy of
the zodiacal light model.Comment: 16 pages, 17 figures, accepted for publication in ApJ (Suppl). Higher
resolution version available at
http://www.cita.utoronto.ca/~mamd/IRIS/IrisTechnical.htm
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Shakespeare's Paraliptic Characters
This thesis straddles the intersection of two contemporary topics in Shakespeare scholarship: the newly resurrected practice of character criticism and Shakespeare’s use of meta-rhetorical principles to inform his dramaturgy. The goal of this study is to illustrate how Shakespeare may have used the effect inherent in paralipsis, a rhetorical device he relied on heavily, to craft four often overlooked characters and punctuate the themes of their respective plays. Since the power of paralipsis comes in the trope’s ability to draw attention to something’s absence, suddenly the omitted Falstaff in Henry V, the neglected Cicero in Julius Caesar, the marginalized Fortinbras in Hamlet, and the abandoned Fool in King Lear all take on a greater significance when examined through a paraliptic lens.
For the better part of the last four hundred years, the absences of these seemingly disposable characters have received scant critical attention, and the paltriness of these parts has rarely been granted any artistic merit; instead, the underwhelming – or, in the case of Falstaff in Henry V, nonexistent – roles of these four characters and their unexpected disappearances have long been ascribed to theatrical economy or Shakespeare’s assumed inattentiveness as a playwright. I will contend, though, that these seemingly shallow roles gain considerable depth and dimension when examined paraliptically, and that Shakespeare’s application of this meta-rhetorical effect in crafting these characters fits with his development as artist in the middle part of his career. Therefore, by rooting this study in the long history of inferential character criticism and the mounting research in meta-rhetorical theory, I will examine the centuries of criticism surrounding these four characters, will execute a close reading of their parts, and, in an attempt to find symbolic value in their marginality, will explore the gaping voids their absences leave in their respective plays. By pressing these gaps, this thesis concludes that there is more than meets the eye with these four characters, and when studied paraliptically, they each serve as foils for their protagonists, manipulate Renaissance expectations of character types, and underscore their respective plays’ themes
Consistent Modeling of Rotational Nonequilibrium in a Hybrid Particle-Continuum Method
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106474/1/AIAA2013-3145.pd
Measurement invariance testing of the patient health questionnaire-9 (PHQ-9) across people with and without diabetes mellitus from the NHANES, EHMS and UK Biobank datasets
Background: The prevalence of depression is higher among those with diabetes than in the general population. The Patient Health Questionnaire (PHQ-9) is commonly used to assess depression in people with diabetes, but measurement invariance of the PHQ-9 across groups of people with and without diabetes has not yet been investigated.
Methods: Data from three independent cohorts from the USA (n=1,886 with diabetes, n=4,153 without diabetes), Quebec, Canada (n= 800 with diabetes, n= 2,411 without diabetes), and the UK (n=4,981 with diabetes, n=145,570 without diabetes), were used to examine measurement invariance between adults with and without diabetes. A series of multiple group confirmatory factor analyses were performed, with increasingly stringent model constraints applied to assess configural, equal thresholds, and equal thresholds and loadings invariance, respectively. One-factor and two-factor (somatic and cognitive-affective items) models were examined.
Results: Results demonstrated that the most stringent models, testing equal loadings and thresholds, had satisfactory model fit in the three cohorts for one-factor models (RMSEA = .063 or below and CFI = .978 or above) and two-factor models (RMSEA = .042 or below and CFI = .989 or above).
Limitations: Data were from Western countries only and we could not distinguish between type of diabetes.
Conclusions: Results provide support for measurement invariance between groups of people with and without diabetes, using either a one-factor or a two-factor model. While the two-factor solution has a slightly better fit, the one-factor solution is more parsimonious. Depending on research or clinical needs, both factor structures can be used
GHIGLS: HI mapping at intermediate Galactic latitude using the Green Bank Telescope
This paper introduces the data cubes from GHIGLS, deep Green Bank Telescope
surveys of the 21-cm line emission of HI in 37 targeted fields at intermediate
Galactic latitude. The GHIGLS fields together cover over 1000 square degrees at
9.55' spatial resolution. The HI spectra have an effective velocity resolution
about 1.0 km/s and cover at least -450 < v < +250 km/s. GHIGLS highlights that
even at intermediate Galactic latitude the interstellar medium is very complex.
Spatial structure of the HI is quantified through power spectra of maps of the
column density, NHI. For our featured representative field, centered on the
North Ecliptic Pole, the scaling exponents in power-law representations of the
power spectra of NHI maps for low, intermediate, and high velocity gas
components (LVC, IVC, and HVC) are -2.86 +/- 0.04, -2.69 +/- 0.04, and -2.59
+/- 0.07, respectively. After Gaussian decomposition of the line profiles, NHI
maps were also made corresponding to the narrow-line and broad-line components
in the LVC range; for the narrow-line map the exponent is -1.9 +/- 0.1,
reflecting more small scale structure in the cold neutral medium (CNM). There
is evidence that filamentary structure in the HI CNM is oriented parallel to
the Galactic magnetic field. The power spectrum analysis also offers insight
into the various contributions to uncertainty in the data. The effect of 21-cm
line opacity on the GHIGLS NHI maps is estimated.Comment: Accepted for publication in The Astrophysical Journal, 2015 July 16.
32 pages, 21 figures (Fig. 10 new). Minor revisions from review, particularly
Section 8 and Appendix C; results unchanged. Additional surveys added and
made available; new Appendix B. Added descriptions of available FITS files
and links to four illustrative movies on enhanced GHIGLS archive
(www.cita.utoronto.ca/GHIGLS/
Rotational Correlation Functions of Single Molecules
Single molecule rotational correlation functions are analyzed for several
reorientation geometries. Even for the simplest model of isotropic rotational
diffusion our findings predict non-exponential correlation functions to be
observed by polarization sensitive single molecule fluorescence microscopy.
This may have a deep impact on interpreting the results of molecular
reorientation measurements in heterogeneous environments.Comment: 5 pages, 4 figure
Analysis of Diffusion of Ras2 in Saccharomyces cerevisiae Using Fluorescence Recovery after Photobleaching
Binding, lateral diffusion and exchange are fundamental dynamic processes
involved in protein association with cellular membranes. In this study, we
developed numerical simulations of lateral diffusion and exchange of
fluorophores in membranes with arbitrary bleach geometry and exchange of the
membrane localized fluorophore with the cytosol during Fluorescence Recovery
after Photobleaching (FRAP) experiments. The model simulations were used to
design FRAP experiments with varying bleach region sizes on plasma-membrane
localized wild type GFP-Ras2 with a dual lipid anchor and mutant GFP-Ras2C318S
with a single lipid anchor in live yeast cells to investigate diffusional
mobility and the presence of any exchange processes operating in the time scale
of our experiments. Model parameters estimated using data from FRAP experiments
with a 1 micron x 1 micron bleach region-of-interest (ROI) and a 0.5 micron x
0.5 micron bleach ROI showed that GFP-Ras2, single or dual lipid modified,
diffuses as single species with no evidence of exchange with a cytoplasmic
pool. This is the first report of Ras2 mobility in yeast plasma membrane. The
methods developed in this study are generally applicable for studying diffusion
and exchange of membrane associated fluorophores using FRAP on commercial
confocal laser scanning microscopes.Comment: Accepted for publication in Physical Biology (2010). 28 pages, 7
figures, 3 table
Excitation lines and the breakdown of Stokes-Einstein relations in supercooled liquids
By applying the concept of dynamical facilitation and analyzing the
excitation lines that result from this facilitation, we investigate the origin
of decoupling of transport coefficients in supercooled liquids. We illustrate
our approach with two classes of models. One depicts diffusion in a strong
glass former, and the other in a fragile glass former. At low temperatures,
both models exhibit violation of the Stokes-Einstein relation,
, where is the self diffusion constant and is the
structural relaxation time. In the strong case, the violation is sensitive to
dimensionality , going as for , and as for . In the fragile case, however, we argue that
dimensionality dependence is weak, and show that for , . This scaling for the fragile case compares favorably with the
results of a recent experimental study for a three-dimensional fragile glass
former.Comment: 7 pages, 7 figures, submitted to Phys. Rev.
Identification of Protein Palmitoylation Inhibitors from a Scaffold Ranking Library
The addition of palmitoyl moieties to proteins regulates their membrane targeting, subcellular localization, and stability. Dysregulation of the enzymes which catalyzed the palmitoyl addition and/or the substrates of these enzymes have been linked to cancer, cardiovascular, and neurological disorders, implying these enzymes and substrates are valid targets for pharmaceutical intervention. However, current chemical modulators of zDHHC PAT enzymes lack specificity and affinity, underscoring the need for screening campaigns to identify new specific, high affinity modulators. This report describes a mixture based screening approach to identify inhibitors of Erf2 activity. Erf2 is the Saccharomyces cerevisiae PAT responsible for catalyzing the palmitoylation of Ras2, an ortholog of the human Ras oncogene proteins. A chemical library developed by the Torrey Pines Institute for Molecular Studies consists of more than 30 million compounds designed around 68 molecular scaffolds that are systematically arranged into positional scanning and scaffold ranking formats. We have used this approach to identify and characterize several scaffold backbones and R-groups that reduce or eliminate the activity of Erf2 in vitro. Here, we present the analysis of one of the scaffold backbones, bis-cyclic piperazine. We identified compounds that inhibited Erf2 auto-palmitoylation activity using a fluorescence-based, coupled assay in a high throughput screening (HTS) format and validated the hits utilizing an orthogonal gel-based assay. Finally, we examined the effects of the compounds on cell growth in a yeast cell-based assay. Based on our results, we have identified specific, high affinity palmitoyl transferase inhibitors that will serve as a foundation for future compound design
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