1,155 research outputs found
Adaptive Optics Simulations for Siding Spring
Using an observational derived model optical turbulence profile (model-OTP)
we have investigated the performance of Adaptive Optics (AO) at Siding Spring
Observatory (SSO), Australia. The simulations cover the performance for AO
techniques of single conjugate adaptive optics (SCAO), multi-conjugate adaptive
optics (MCAO) and ground-layer adaptive optics (GLAO). The simulation results
presented in this paper predict the performance of these AO techniques as
applied to the Australian National University (ANU) 2.3 m and Anglo-Australian
Telescope (AAT) 3.9 m telescopes for astronomical wavelength bands J, H and K.
The results indicate that AO performance is best for the longer wavelengths
(K-band) and in the best seeing conditions (sub 1-arcsecond). The most
promising results are found for GLAO simulations (field of view of 180
arcsecs), with the field RMS for encircled energy 50% diameter (EE50d) being
uniform and minimally affected by the free-atmosphere turbulence. The GLAO
performance is reasonably good over the wavelength bands of J, H and K. The
GLAO field mean of EE50d is between 200 mas to 800 mas, which is a noticeable
improvement compared to the nominal astronomical seeing (870 to 1700 mas).Comment: 15 pages; accepted for publication in PAS
Expert system verification concerns in an operations environment
The Space Shuttle community is currently developing a number of knowledge-based tools, primarily expert systems, to support Space Shuttle operations. It is proposed that anticipating and responding to the requirements of the operations environment will contribute to a rapid and smooth transition of expert systems from development to operations, and that the requirements for verification are critical to this transition. The paper identifies the requirements of expert systems to be used for flight planning and support and compares them to those of existing procedural software used for flight planning and support. It then explores software engineering concepts and methodology that can be used to satisfy these requirements, to aid the transition from development to operations and to support the operations environment during the lifetime of expert systems. Many of these are similar to those used for procedural hardware
Some Aspects of the Interaction of Speaker and Hearer in the Construction of the Turn at Talk in Natural Conversation
Abstract not availabl
PI3K in juvenile myelomonocytic leukemia
Indiana University-Purdue University Indianapolis (IUPUI)Juvenile Myelomonocytic Leukemia (JMML) is rare, fatal myeloproliferative disease (MPD) affecting young children, and is characterized by expansion of monocyte lineage cells and hypersensitivity to Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) stimulation. JMML is frequently associated with gain-of-function mutations in the PTPN11 gene, which encodes the protein tyrosine phosphatase, Shp2. Activating Shp2 mutations are known to promote hyperactivation of the Ras-Erk signaling pathway, but Akt is also observed to have enhanced phosphorylation, suggesting a potential role for Phosphatidylinositol-3-Kinase (PI3K)-Akt signaling in mutant Shp2-induced GM-CSF hypersensitivity and leukemogenesis.
Having demonstrated that Class IA PI3K is hyperactivated in the presence of mutant Shp2 and contributes to GM-CSF hypersensitivity, I hypothesized the hematopoietic-specific Class IA PI3K catalytic subunit p110δ is a crucial mediator of mutant Shp2-induced PI3K hyperactivation and GM-CSF hypersensitivity in vitro and MPD development in vivo. I crossed gain-of-function mutant Shp2 D61Y inducible knockin mice, which develop fatal MPD, with mice expressing kinase-dead mutant p110δ D910A to evaluate p110δ’s role in mutant Shp2-induced GM-CSF hypersensitivity in vitro and MPD development in vivo. As a comparison, I also crossed Shp2 D61Y inducible knockin mice with mice bearing inducible knockout of the ubiquitously expressed Class IA PI3K catalytic subunit, p110α. I found that genetic interruption of p110δ, but not p110α, significantly reduced GM-CSF-stimulated hyperactivation of both the Ras-Erk and PI3K-Akt signaling pathways, and as a consequence, resulted in reduced GM-CSF-stimulated hyper-proliferation in vitro. Furthermore, I found that mice bearing genetic disruption of p110δ, but not p110α, in the presence of gain-of-function mutant Shp2 D61Y, had on average, smaller spleen sizes, suggesting that loss of p110δ activity reduced MPD severity in vivo.
I also investigated the effects of three PI3K inhibitors with high specificity for p110δ, IC87114, GDC-0941, and GS-9820 (formerly known as CAL-120), on mutant Shp2-induced GM-CSF hypersensitivity. These inhibitors with high specificity for p110δ significantly reduced GM-CSF-stimulated hyperactivation of PI3K-Akt and Ras-Erk signaling and reduced GM-CSF-stimulated hyperproliferation in cells expressing gain-of-function Shp2 mutants.
Collectively, these findings show that p110δ-dependent PI3K hyperactivation contributes to mutant Shp2-induced GM-CSF hypersensitivity and MPD development, and that p110δ represents a potential novel therapeutic target for JMML
That brief
pamphletReply to A. M. Gibson's pamphlet entitled, "Brief in re Senate bill number 10.
Improved detection of atmospheric turbulence with SLODAR
We discuss several improvements in the detection of atmospheric
turbulence using SLOpe Detection And Ranging (SLODAR).
Frequently, SLODAR observations have shown strong ground-layer
turbulence, which is beneficial to adaptive optics. We show that current
methods which neglect atmospheric propagation effects can underestimate
the strength of high altitude turbulence by up to ~ 30%. We show that
mirror and dome seeing turbulence can be a significant fraction of measured
ground-layer turbulence, some cases up to ~ 50%. We also demonstrate
a novel technique to improve the nominal height resolution, by a factor
of 3, called Generalized SLODAR. This can be applied when sampling
high-altitude turbulence, where the nominal height resolution is the poorest,
or for resolving details in the important ground-layer
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