397 research outputs found
A Mandated Minimum Competency Testing Program and Its Impact on Learning Disabled Students: Curricular Validity and Comparative Performances
This research was published by the KU Center for Research on Learning, formerly known as the University of Kansas Institute for Research in Learning Disabilities.In this study, LD specialists, regular class teachers, and parents of LD students judged that the objectives of the Kansas Minimum Competency Specifications prescribed for nonhandicapped students were applicable to LD students. In addition, the Kansas Minimal Competency Test was administered to LD students under standard and oral conditions. Results showed that they did not perform as well as their nonhandicapped peers at any of the five grade levels. The test was then administered under two modified conditions. Learning disabled students' performance on some objectives at every grade level was not improved by either administering items orally or administering the test one grade level above that designated for nonhandicapped students
Chandra Orion Ultradeep Project: Observations and Source Lists
We present a description of the data reduction methods and the derived
catalog of more than 1600 X-ray point sources from the exceptionally deep
January 2003 Chandra X-ray Observatory observation of the Orion Nebula Cluster
and embedded populations around OMC-1. The observation was obtained with
Chandra's Advanced CCD Imaging Spectrometer (ACIS) and has been nicknamed the
Chandra Orion Ultradeep Project (COUP). With an 838 ks exposure made over a
continuous period of 13.2 days, the COUP observation provides the most uniform
and comprehensive dataset on the X-ray emission of normal stars ever obtained
in the history of X-ray astronomy.Comment: 52 pages, 11 figures, 12 tables. Accepted for publication in ApJS,
special issue dedicated to Chandra Orion Ultradeep Project. A version with
high quality figures can be found at
http://www.astro.psu.edu/users/gkosta/COUP_Methodology.pd
A multiwavelength investigation of the massive eclipsing binary Cyg OB2 #5
The properties of the early-type binary Cyg OB2 #5 have been debated for many
years and spectroscopic and photometric investigations yielded conflicting
results. We have attempted to constrain the physical properties of the binary
by collecting new optical and X-ray observations. We find that the orbital
period of the system slowly changes though we are unable to discriminate
between several possible explanations of this trend. The best fit solution of
the continuum light curve reveals a contact configuration with the secondary
star being significantly brighter and hotter on its leading side facing the
primary. The mean temperature of the secondary star turns out to be only
slightly lower than that of the primary, whilst the bolometric luminosity ratio
is found to be 3.1. The solution of the light curve yields a distance of 925
+/- 25 pc much lower than the usually assumed distance of the Cyg OB2
association. Whilst we confirm the existence of episodes of higher X-ray
fluxes, the data reveal no phase-locked modulation with the 6.6 day period of
the eclipsing binary nor any clear relation between the X-ray flux and the 6.7
yr radio cycle. The bright region of the secondary star is probably heated by
energy transfer in a common envelope in this contact binary system as well as
by the collision with the primary's wind. The existence of a common photosphere
probably also explains the odd mass-luminosity relation of the stars in this
system. Most of the X-ray, non-thermal radio, and possibly gamma-ray emission
of Cyg OB2 #5 is likely to arise from the interaction of the combined wind of
the eclipsing binary with at least one additional star of this multiple system
A study of cytokeratin 20 immunostaining in the urothelium of neuropathic bladder of patients with spinal cord injury
BACKGROUND: Normal urothelium is characterised by terminally differentiated superficial cells, which express cytokeratin 20 in the cytoplasm. In contrast, cultured human stratified urothelium, which does not undergo complete terminal differentiation of its superficial cells, does not express cytokeratin 20. If spinal cord injury (SCI) affects urothelial differentiation or induces squamous or other metaplastic change undetected by histological analysis, the superficial urothelial cells of the neuropathic bladder might be expected to show absence of immunostaining for cytokeratin 20. PATIENTS AND METHODS: We studied immunostaining for cytokeratin 20 in bladder biopsies taken from 63 consecutive SCI patients. Immunostaining was performed on paraffin-embedded tissue using a mouse monoclonal antibody (clone: Ks20.8). RESULTS: Of 63 biopsies, the epithelium was scarce in two. Eight biopsies showed squamous metaplasia and immunostaining for cytokeratin 20 was absent in all the eight biopsies. Of the remaining 53 cases, in which the umbrella cell layer of the urothelium was intact, immunostaining for cytokeratin 20 was seen only in ten biopsies. CONCLUSION: Superficial cells in the transitional epithelium showed immunostaining for cytokeratin 20 in 10 of 53 bladder biopsies taken from SCI patients. The reasons for this could be either that there is an underlying metaplasia or that changes in the neuropathic bladder affect urothelial differentiation. Taken with evidence from other systems, such as loss of cytokeratin 20 expression from static organ cultures of urothelial tissue, this might suggest that other factors, such as impairment of voluntary voiding in SCI patients, could affect expression of markers such as cytokeratin 20
Loss of chromosome Y leads to down regulation of KDM5D and KDM6C epigenetic modifiers in clear cell renal cell carcinoma
Recent genomic studies of sporadic clear cell renal cell carcinoma (ccRCC) have uncovered novel driver genes and pathways. Given the unequal incidence rates among men and women (male:female incidence ratio approaches 2:1), we compared the genome-wide distribution of the chromosomal abnormalities in both sexes. We observed a higher frequency for the somatic recurrent chromosomal copy number variations (CNVs) of autosomes in male subjects, whereas somatic loss of chromosome X was detected exclusively in female patients (17.1%). Furthermore, somatic loss of chromosome Y (LOY) was detected in about 40% of male subjects, while mosaic LOY was detected in DNA isolated from peripheral blood in 9.6% of them, and was the only recurrent CNV in constitutional DNA samples. LOY in constitutional DNA, but not in tumor DNA was associated with older age. Amongst Y-linked genes that were downregulated due to LOY, KDM5D and KDM6C epigenetic modifiers have functionally-similar X-linked homologs whose deficiency is involved in ccRCC progression. Our findings establish somatic LOY as a highly recurrent genetic defect in ccRCC that leads to downregulation of hitherto unsuspected epigenetic factors, and suggest that different mechanisms may underlie the somatic and mosaic LOY observed in tumors and peripheral blood, respectively
High Resolution X-ray Spectroscopy of the Post-T Tauri Star PZ Tel
We present an analysis of the Chandra High Energy Transmission Grating
Spectrometer observation of the rapidly rotating P_(rot)=0.94 d post T Tauri
(~20 Myr old) star PZ Telescopii, in the Tucana association. Using two
different methods we have derived the coronal emission measure distribution,
em(T), and chemical abundances. The em(T) peaks at log T = 6.9 and exhibits a
significant emission measure at temperatures log T > 7. The coronal abundances
are generally ~0.5 times the solar photospheric values that are presumed fairly
representative of the composition of the underlying star. A minimum in
abundance is seen at a first ionization potential (FIP) of 7-8 eV, with
evidence for higher abundances at both lower and higher FIP, similar to
patterns seen in other active stars. From an analysis of the He-like triplet of
Mg XI we have estimated electron densities of ~10^(12)-10^(13) cm^(-3). All the
coronal properties found for PZ Tel are much more similar to those of AB Dor,
which is slightly older than PZ Tel, than to those of the younger T Tauri star
TW Hya. These results support earlier conclusions that the soft X-ray emission
of TW Hya is likely dominated by accretion activity rather than by a
magnetically-heated corona. Our results also suggest that the coronae of
pre-main sequence stars rapidly become similar to those of older active
main-sequence stars soon after the accretion stage has ended.Comment: 15 pages, 8 Postscript figures, accepted for publication in
Astrophysical Journa
Tumor Heterogeneity of Fibroblast Growth Factor Receptor 3 (FGFR3) Mutations in Invasive Bladder Cancer: Implications for Peri-Operative anti-FGFR3 Treatment
Background: Fibroblast growth factor receptor 3 (FGFR3) is an actionable target in bladder cancer. Preclinical studies show that anti-FGFR3 treatment slows down tumor growth, suggesting that this tyrosine kinase receptor is a candidate for personalized bladder cancer treatment, particularly in patients with mutated FGFR3. We addressed tumor heterogeneity in a large multicenter, multi-laboratory study, as this may have significant impact on therapeutic response. Patients: and methods We evaluated possible FGFR3 heterogeneity by the PCR-SNaPshot method in the superficial and deep compartments of tumors obtained by transurethral resection (TUR, n = 61) and in radical cystectomy (RC, n = 614) specimens and corresponding cancer-positive lymph nodes (LN+, n = 201).Results: We found FGFR3 mutations in 13/34 (38%) T1 and 8/27 (30%) ≥T2-TUR samples, with 100% concordance between superficial and deeper parts in T1-TUR samples. Of eight FGFR3 mutant ≥T2-TUR samples, only 4 (50%) displayed the mutation in the deeper part. We found 67/614 (11%) FGFR3 mutations in RC specimens. FGFR3 mutation was associated with pN0 (P < 0.001) at RC. In 10/201 (5%) LN+, an FGFR3 mutation was found, all concordant with the corresponding RC specimen. In the remaining 191 cases, RC and LN+ were both wild type.Conclusions: FGFR3 mutation status seems promising to guide decision-making on adjuvant anti-FGFR3 therapy as it appeared homogeneous in RC and LN+. Based on the results of TUR, the deep part of the tumor needs to be assessed if neoadjuvant anti-FGFR3 treatment is considered. We conclude that studies on the heterogeneity of actionable molecular targets should precede clinical trials with these drugs in the perioperative setting
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