2,720 research outputs found
FGFR1 amplifi cation and the progression of non-invasive to invasive breast cancer
The incidence of invasive breast cancer (IBC) can be dramatically reduced by improving our abilities to detect and treat ductal carcinoma in situ (DCIS). Progress will be based on a detailed understanding of molecular mechanisms responsible for tumor progression. An interesting study by Jang and colleagues evaluated and compared the frequency of amplification of four oncogenes (HER2, c-MYC, CCND1 and FGFR1) in large cohorts of pure DCIS, in the DCIS component of IBC, and in corresponding IBC. Of particular interest, they found a twofold increase in FGFR1 amplification in IBC versus pure DCIS, and significantly reduced disease-free survival in amplified versus unamplified IBC - leading the authors to conclude that FGFR1 plays an important role in the development and progression of IBC. These observations indeed provide hints that FGFR1 is important in this setting, although the issue is very complex and far from resolved
Hydrogen Balmer Line Broadening in Solar and Stellar Flares
The broadening of the hydrogen lines during flares is thought to result from
increased charge (electron, proton) density in the flare chromosphere. However,
disagreements between theory and modeling prescriptions have precluded an
accurate diagnostic of the degree of ionization and compression resulting from
flare heating in the chromosphere. To resolve this issue, we have incorporated
the unified theory of electric pressure broadening of the hydrogen lines into
the non-LTE radiative transfer code RH. This broadening prescription produces a
much more realistic spectrum of the quiescent, A0 star Vega compared to the
analytic approximations used as a damping parameter in the Voigt profiles. We
test recent radiative-hydrodynamic (RHD) simulations of the atmospheric
response to high nonthermal electron beam fluxes with the new broadening
prescription and find that the Balmer lines are over-broadened at the densest
times in the simulations. Adding many simultaneously heated and cooling model
loops as a "multithread" model improves the agreement with the observations. We
revisit the three-component phenomenological flare model of the YZ CMi
Megaflare using recent and new RHD models. The evolution of the broadening,
line flux ratios, and continuum flux ratios are well-reproduced by a
multithread model with high-flux nonthermal electron beam heating, an extended
decay phase model, and a "hot spot" atmosphere heated by an ultrarelativistic
electron beam with reasonable filling factors: 0.1%, 1%, and 0.1% of the
visible stellar hemisphere, respectively. The new modeling motivates future
work to understand the origin of the extended gradual phase emission.Comment: 31 pages, 13 figures, 2 tables, accepted for publication in the
Astrophysical Journa
LaRC design analysis report for National Transonic Facility for 304 stainless steel tunnel shell. Volume 4S: Thermal analysis
For abstract, see N76-33552
LaRC design analysis report for National Transonic Facility for 304 stainless steel tunnel shell. Volume 7S: Special studies
For abstract, see N76-33552
The Implications of M Dwarf Flares on the Detection and Characterization of Exoplanets at Infrared Wavelengths
We present the results of an observational campaign which obtained high time
cadence, high precision, simultaneous optical and IR photometric observations
of three M dwarf flare stars for 47 hours. The campaign was designed to
characterize the behavior of energetic flare events, which routinely occur on M
dwarfs, at IR wavelengths to milli-magnitude precision, and quantify to what
extent such events might influence current and future efforts to detect and
characterize extrasolar planets surrounding these stars. We detected and
characterized four highly energetic optical flares having U-band total energies
of ~7.8x10^30 to ~1.3x10^32 ergs, and found no corresponding response in the J,
H, or Ks bandpasses at the precision of our data. For active dM3e stars, we
find that a ~1.3x10^32 erg U-band flare (delta Umax ~1.5 mag) will induce <8.3
(J), <8.5 (H), and <11.7 (Ks) milli-mags of a response. A flare of this energy
or greater should occur less than once per 18 hours. For active dM4.5e stars,
we find that a ~5.1x10^31 erg U-band flare (delta Umax ~1.6 mag) will induce
<7.8 (J), <8.8 (H), and <5.1 (Ks) milli-mags of a response. A flare of this
energy or greater should occur less than once per 10 hours. No evidence of
stellar variability not associated with discrete flare events was observed at
the level of ~3.9 milli-mags over 1 hour time-scales and at the level of ~5.6
milli-mags over 7.5 hour time-scales. We therefore demonstrate that most M
dwarf stellar activity and flares will not influence IR detection and
characterization studies of M dwarf exoplanets above the level of ~5-11
milli-mags, depending on the filter and spectral type. We speculate that the
most energetic megaflares on M dwarfs, which occur at rates of once per month,
are likely to be easily detected in IR observations with sensitivity of tens of
milli-mags.Comment: Accepted in Astronomical Journal, 17 pages, 6 figure
Topological Surface States and Dirac point tuning in ternary Bi2Te2Se class of topological insulators
Using angle-resolved photoemission spectroscopy, we report electronic
structure for representative members of ternary topological insulators. We show
that several members of this family, such as Bi2Se2Te, Bi2Te2Se, and GeBi2Te4,
exhibit a singly degenerate Dirac-like surface state, while Bi2Se2S is a fully
gapped insulator with no measurable surface state. One of these compounds,
Bi2Se2Te, shows tunable surface state dispersion upon its electronic alloying
with Sb (SbxBi2-xSe2Te series). Other members of the ternary family such as
GeBi2Te4 and BiTe1.5S1.5 show an in-gap surface Dirac point, the former of
which has been predicted to show nonzero weak topological invariants such as
(1;111); thus belonging to a different topological class than BiTe1.5S1.5. The
measured band structure presented here will be a valuable guide for
interpreting transport, thermoelectric, and thermopower measurements on these
compounds. The unique surface band topology observed in these compounds
contributes towards identifying designer materials with desired flexibility
needed for thermoelectric and spintronic device fabrication.Comment: 9 pages, 6 figures; Related results at
http://online.kitp.ucsb.edu/online/topomat11/hasan
Solar Ellerman Bombs in 1D Radiative Hydrodynamics
Recent observations from the Interface Region Imaging Spectrograph (IRIS) appear to show impulsive brightenings in high temperature lines, which when combined with simultaneous ground based observations in Hα, appear co-spatial to Ellerman Bombs (EBs). We use the RADYN 1-dimensional radiative transfer code in an attempt to try and reproduce the observed line profiles and simulate the atmospheric conditions of these events. Combined with the MULTI/RH line synthesis codes, we compute the Hα, Ca II 8542 A, and Mg II h & k lines for these simulated events and compare them to previous observations. Our findings hint that the presence of superheated regions in the photosphere (>10,000 K) is not a plausible explanation for the production of EB signatures. While we are able to recreate EB-like line profiles in Hα, Ca II 8542 A, and Mg II h & k, we cannot achieve agreement with all of these simultaneously
Comparing computer-generated and pathologist-generated tumour segmentations for immunohistochemical scoring of breast tissue microarrays
BACKGROUND: Tissue microarrays (TMAs) have become a valuable resource for biomarker expression in translational research. Immunohistochemical (IHC) assessment of TMAs is the principal method for analysing large numbers of patient samples, but manual IHC assessment of TMAs remains a challenging and laborious task. With advances in image analysis, computer-generated analyses of TMAs have the potential to lessen the burden of expert pathologist review. METHODS: In current commercial software computerised oestrogen receptor (ER) scoring relies on tumour localisation in the form of hand-drawn annotations. In this study, tumour localisation for ER scoring was evaluated comparing computer-generated segmentation masks with those of two specialist breast pathologists. Automatically and manually obtained segmentation masks were used to obtain IHC scores for thirty-two ER-stained invasive breast cancer TMA samples using FDA-approved IHC scoring software. RESULTS: Although pixel-level comparisons showed lower agreement between automated and manual segmentation masks (κ=0.81) than between pathologists' masks (κ=0.91), this had little impact on computed IHC scores (Allred; [Image: see text]=0.91, Quickscore; [Image: see text]=0.92). CONCLUSIONS: The proposed automated system provides consistent measurements thus ensuring standardisation, and shows promise for increasing IHC analysis of nuclear staining in TMAs from large clinical trials
Management Activities of Private Forest Landowners in New York State
CaRDI Research & Policy Brief, Issue 15. Click on the PDF for the full report. Visit the HDRU website for a complete listing of HDRU publications at: http://hdru.dnr.cornell.edu/. A complete listing of CaRDI publications can be found on its site: https://cardi.cals.cornell.edu/
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