3,104 research outputs found
Promoting Partnerships for Student Success: Lessons from the SSPIRE Initiative
The Student Support Partnership Integrating Resources and Education (SSPIRE) initiative aimed to increase the success of young, low-income, and academically underprepared California community college students by helping colleges strengthen their support services and better integrate these services with academic instruction. This report describes what the nine participating community colleges did to meet the goals of SSPIRE and offers lessons for other institutions drawn from MDRC's research on the initiative
Conformational switching in the coiled-coil domains of a proteasomal ATPase regulates substrate processing
Protein degradation in all domains of life requires ATPases that unfold and inject proteins into compartmentalized proteolytic chambers. Proteasomal ATPases in eukaryotes and archaea contain poorly understood N-terminally conserved coiled-coil domains. In this study, we engineer disulfide crosslinks in the coiled-coils of the archaeal proteasomal ATPase (PAN) and report that its three identical coiled-coil domains can adopt three different conforma- tions: (1) in-register and zipped, (2) in-register and partially unzipped, and (3) out-of-register. This conformational heterogeneity conflicts with PAN’s symmetrical OB-coiled-coil crystal structure but resembles the conformational heterogeneity of the 26S proteasomal ATPases’ coiled-coils. Furthermore, we find that one coiled-coil can be conformationally constrained even while unfolding substrates, and conformational changes in two of the coiled-coils reg- ulate PAN switching between resting and active states. This switching functionally mimics similar states proposed for the 26S proteasome from cryo-EM. These findings thus build a mechanistic framework to understand regulation of proteasome activity
MLI: An API for Distributed Machine Learning
MLI is an Application Programming Interface designed to address the
challenges of building Machine Learn- ing algorithms in a distributed setting
based on data-centric computing. Its primary goal is to simplify the
development of high-performance, scalable, distributed algorithms. Our initial
results show that, relative to existing systems, this interface can be used to
build distributed implementations of a wide variety of common Machine Learning
algorithms with minimal complexity and highly competitive performance and
scalability
Walter E. Treanor Memorial Addresses
The Walter E. Treanor Memorial Issue
At the regular term of the United States Circuit Court of Appeals for the Seventh Circuit the following Memorial Resolutions were presented on April 14th, 1942
Quasars: What turns them off?
(Abridged) We explore the idea that the anti-hierarchical turn-off observed
in the quasar population arises from self-regulating feedback, via an outflow
mechanism. Using a detailed hydrodynamic simulation we calculate the luminosity
function of quasars down to a redshift of z=1 in a large, cosmologically
representative volume. Outflows are included explicitly by tracking halo
mergers and driving shocks into the surrounding intergalactic medium. Our
results are in excellent agreement with measurements of the spatial
distribution of quasars, and we detect an intriguing excess of galaxy-quasar
pairs at very short separations. We also reproduce the anti-hierarchical
turnoff in the quasar luminosity function, however, the magnitude of the
turn-off falls short of that observed as well as that predicted by analogous
semi-analytic models. The difference can be traced to the treatment of gas
heating within galaxies. The simulated galaxy cluster L_X-T relationship is
close to that observed for z~1 clusters, but the simulated galaxy groups at z=1
are significantly perturbed by quasar outflows, suggesting that measurements of
X-ray emission in high-redshift groups could well be a "smoking gun" for the
AGN heating hypothesis.Comment: 16 pages, 11 figures, submitted to ApJ, comments welcome
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