15,532 research outputs found
Development of a Translator from LLVM to ACL2
In our current work a library of formally verified software components is to
be created, and assembled, using the Low-Level Virtual Machine (LLVM)
intermediate form, into subsystems whose top-level assurance relies on the
assurance of the individual components. We have thus undertaken a project to
build a translator from LLVM to the applicative subset of Common Lisp accepted
by the ACL2 theorem prover. Our translator produces executable ACL2 formal
models, allowing us to both prove theorems about the translated models as well
as validate those models by testing. The resulting models can be translated and
certified without user intervention, even for code with loops, thanks to the
use of the def::ung macro which allows us to defer the question of termination.
Initial measurements of concrete execution for translated LLVM functions
indicate that performance is nearly 2.4 million LLVM instructions per second on
a typical laptop computer. In this paper we overview the translation process
and illustrate the translator's capabilities by way of a concrete example,
including both a functional correctness theorem as well as a validation test
for that example.Comment: In Proceedings ACL2 2014, arXiv:1406.123
Gas, Iron and Gravitational Mass in Galaxy Clusters: The General Lack of Cluster Evolution at z < 1.0
We have analyzed the ASCA data of 29 nearby clusters of galaxies
systematically, and obtained temperatures, iron abundances, and X-ray
luminosities of their intracluster medium (ICM). We also estimate ICM mass
using the beta model, and then evaluate iron mass contained in the ICM and
derive the total gravitating mass. This gives the largest and most homogeneous
information about the ICM derived only by the ASCA data. We compare these
values with those of distant clusters whose temperatures, abundances, and
luminosities were also measured with ASCA, and find no clear evidence of
evolution for the clusters at z<1.0. Only the most distant cluster at z=1.0,
AXJ2019.3+1127, has anomalously high iron abundance, but its iron mass in the
ICM may be among normal values for the other clusters, because the ICM mass may
be smaller than the other clusters. This may suggest a hint of evolution of
clusters at z ~ 1.0.Comment: 23 pages including 5 figures. Using PASJ2.sty, and PASJ95.sty.
Accepted by PAS
Temporal Recurrent Networks for Online Action Detection
Most work on temporal action detection is formulated as an offline problem,
in which the start and end times of actions are determined after the entire
video is fully observed. However, important real-time applications including
surveillance and driver assistance systems require identifying actions as soon
as each video frame arrives, based only on current and historical observations.
In this paper, we propose a novel framework, Temporal Recurrent Network (TRN),
to model greater temporal context of a video frame by simultaneously performing
online action detection and anticipation of the immediate future. At each
moment in time, our approach makes use of both accumulated historical evidence
and predicted future information to better recognize the action that is
currently occurring, and integrates both of these into a unified end-to-end
architecture. We evaluate our approach on two popular online action detection
datasets, HDD and TVSeries, as well as another widely used dataset, THUMOS'14.
The results show that TRN significantly outperforms the state-of-the-art
Molecular manipulation of keratin 8/18 intermediate filaments: modulators of FAS-mediated death signaling in human ovarian granulosa tumor cells
Background: Granulosa cell tumors (GCT) are a rare ovarian neoplasm but prognosis is poor following recurrence. Keratin intermediate filaments expressed in these tumors are a diagnostic marker, yet paradoxically, may also constitute a target for therapeutic intervention. In the current study, we evaluated keratin 8/18 (K8/18) filament expression as a mechanism of resistance to apoptosis in GCT, specifically focusing on regulation of the cell surface death receptor, Fas (FAS).
Methods: The GCT cell line, KGN, was transiently transfected with siRNA to KRT8 and KRT18 to reduce K8/18 filament expression. Expression of K8/18, FAS, and apoptotic proteins (PARP, cleaved PARP) were evaluated by fluorescence microscopy, flow cytometric analysis, and immunoblotting, respectively. The incidence of FAS-mediated apoptosis in KGN cells was measured by caspase 3/7 activity. All experiments were performed independently three to six times, using a fresh aliquot of KGN cells for each experiment. Quantitative data were analyzed by one- or two-way analysis of variance (ANOVA), followed by a Tukey’s post-test for multiple comparisons; differences among means were considered statistically significant at P \u3c 0.05.
Results: Control cultures of KGN cells exhibited abundant K8/18 filament expression (~90 % of cells), and minimal expression of FAS (\u3c25 % of cells). These cells were resistant to FAS-activating antibody (FasAb)-induced apoptosis, as determined by detection of cleaved PARP and measurement of caspase 3/7 activity. Conversely, siRNA-mediated knock-down of K8/18 filament expression enhanced FAS expression (\u3e 70 % of cells) and facilitated FasAb-induced apoptosis, evident by increased caspase 3/7 activity (P \u3c 0.05). Additional experiments revealed that inhibition of protein synthesis, but not MEK1/2 or PI3K signaling, also prompted FasAb-induced apoptosis.
Conclusions: The results demonstrated that K8/18 filaments provide resistance to apoptosis in GCT by impairing FAS expression. The abundance of keratin filaments in these cells and their role in apoptotic resistance provides a greater mechanistic understanding of ovarian tumorgenicity, specifically GCT, as well as a clinically-relevant target for potential therapeutic intervention
The Effect of Ambimorphic Epistemologies on Robotics
In recent years, much research has been devoted to the development of operating systems; nevertheless, few have deployed the deployment of evolutionary programming. Given the trends in event-driven technology, system administrators famously note the evaluation of gigabit switches, which embodies the unproven principles of machine learning. In order to overcome this grand challenge, we construct new client-server communication (FaecalSwatch), which we use to argue that the well-known interactive algorithm for the emulation of online algorithms by F. R. Anderson [7] runs in Ω(n2) time
The Enrichment History of Hot Gas in Poor Galaxy Groups
We have analyzed the ASCA SIS and GIS data for seventeen groups and
determined the average temperature and abundance of the hot x-ray emitting gas.
For groups with gas temperatures less than 1.5 keV we find that the abundance
is correlated with the gas temperature and luminosity. We have also determined
the abundance of the alpha-elements and iron independently for those groups
with sufficient counts. We find that for the cool groups (i.e. kT <1.5 keV) the
ratio of alpha-elements to iron is ~1, about half that seen in clusters.
Spectral fits with the S, Si and Fe abundances allowed to vary separately
suggest the S/Fe ratio is similar to that seen in clusters while the Si/Fe
ratio in groups is half the value determined for richer systems. The mass of
metals per unit blue luminosity drops rapidly in groups as the temperature
drops. There are two possible explanations for this decrease. One is that the
star formation in groups is very different from that in rich clusters. The
other explanation is that groups lose much of their enriched material via winds
during the early evolution of ellipticals. If the latter is true, we find that
poor groups will have contributed significantly (roughly 1/3 of the metals) to
the enrichment of the intergalactic medium.Comment: 19 Pages with 2 figures, Accepted for publication in the
Astrophysical Journa
X-Ray Emission from M32: X-Ray Binaries or a micro-AGN?
We have analysed archival {\it ROSAT} PSPC data for M32 in order to study the
x-ray emission from this nearest elliptical galaxy. We fit spectra from three
long exposures with Raymond-Smith, thermal bremsstrahlung, and power-law
models. All models give excellent fits. The thermal fits have kT4 keV,
the Raymond-Smith iron abundance is Solar, the power-law
fit has =1.60.1, and all fits have consistent with the
Galactic column. The source is centered on M32 to an accuracy of 9, and
unresolved at 27 FWHM (90 pc). M32 is x-ray variable by a factor of
3--5 on timescales of a decade down to minutes, with evidence for a possible
period of 1.3 days.
There are two plausible interpretations for these results: 1) Emission due to
low-mass x-ray binaries; 2) Emission due to accretion onto a massive central
black hole. Both of these possibilities are supported by arguments based on
previous studies of M32 and other old stellar systems; the {\it ROSAT} PSPC
data do not allow us to unambiguously choose between them. Observations with
the {\it ROSAT} HRI and with {\it ASCA} are required to determine which of
these two very different physical models is correct.Comment: 9 pages, 5 PostScript figures, uses AASTeX style files, Accepted for
publication in Astrophysical Journal Letter
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