540 research outputs found
Developing a Qualia-Based Multi-Agent Architecture for Use in Malware Detection
Detecting network intruders and malicious software is a significant problem for network administrators and security experts. New threats are emerging at an increasing rate, and current signature and statistics-based techniques are not keeping pace. Intelligent systems that can adapt to new threats are needed to mitigate these new strains of malware as they are released. This research detects malware based on its qualia, or essence rather than its low-level implementation details. By looking for the underlying concepts that make a piece of software malicious, this research avoids the pitfalls of static solutions that focus on predefined bit sequence signatures or anomaly thresholds. This research develops a novel, hierarchical modeling method to represent a computing system and demonstrates the representation’s effectiveness by modeling the Blaster worm. Using Latent Dirichlet Allocation and Support Vector Machines abstract concepts are automatically generated that can be used in the hierarchical model for malware detection. Finally, the research outlines a novel system that uses multiple levels of individual software agents that sharing contextual relationships and information across different levels of abstraction to make decisions. This qualia-based system provides a framework for developing intelligent classification and decision-making systems for a number of application areas
p21-Activated Kinase 3 (PAK3) Is an AP-1 Regulated Gene Contributing to Actin Organisation and Migration of Transformed Fibroblasts
Activating Protein 1 (AP-1) plays a vital role in cell proliferation, differentiation and apoptosis. While de-regulation of AP-1 has been linked to many cancers, little is known regarding its downstream transcriptional targets that associate with cellular transformation. Previous studies identified PAK3, a serine/threonine kinase, as a potential AP-1 target gene. PAK3 has been implicated in a variety of pathological disorders and over-expression of other PAK-family members has been linked to cancer. In this study, we investigate AP-1 regulation of PAK3 expression and the role of PAK3 in cJun/AP-1-associated cellular transformation. Our results showed elevated PAK3 expression at both the mRNA and protein level in cJun-over-expressing Rat1a fibroblasts, as well as in transformed human fibroblasts. Elevated PAK3 expression in cJun/AP-1 over-expressing cells associated with a significant increase in PAK3 promoter activation. This increased promoter activity was lost when a single putative Jun binding site, which can bind AP-1 directly both in vitro and in vivo, was mutated. Further, inhibition of PAK3 using siRNA showed a regression in the cell morphology, migratory potential and actin organisation associated with AP-1 transformed cells. Our study is a first to describe a role for AP-1 in regulating PAK3 expression and suggest that PAK3 is an AP-1 target required for actin organization and migration observed in transformed cells
TDCOSMO XI. Automated Modeling of 9 Strongly Lensed Quasars and Comparison Between Lens Modeling Software
To use strong gravitational lenses as an astrophysical or cosmological probe,
models of their mass distributions are often needed. We present a new,
time-efficient automation code for uniform modeling of strongly lensed quasars
with GLEE, a lens modeling software, for high-resolution multi-band data. By
using the observed positions of the lensed quasars and the spatially extended
surface brightness distribution of the lensed quasar host galaxy, we obtain a
model of the mass distribution of the lens galaxy. We apply this uniform
modeling pipeline to a sample of nine strongly lensed quasars with HST WFC 3
images. The models show in most cases well reconstructed light components and a
good alignment between mass and light centroids. We find that the automated
modeling code significantly reduces the user input time during the modeling
process. The preparation time of required input files is reduced significantly.
This automated modeling pipeline can efficiently produce uniform models of
extensive lens system samples which can be used for further cosmological
analysis. A blind test through a comparison with the results of an independent
automated modeling pipeline based on the modeling software Lenstronomy reveals
important lessons. Quantities such as Einstein radius, astrometry, mass
flattening and position angle are generally robustly determined. Other
quantities depend crucially on the quality of the data and the accuracy of the
PSF reconstruction. Better data and/or more detailed analysis will be necessary
to elevate our automated models to cosmography grade. Nevertheless, our
pipeline enables the quick selection of lenses for follow-up monitoring and
further modeling, significantly speeding up the construction of
cosmography-grade models. This is an important step forward to take advantage
of the orders of magnitude increase in the number of lenses expected in the
coming decade.Comment: 36 pages, 13 figures, submitted to A&
H0LiCOW XII. Lens mass model of WFI2033-4723 and blind measurement of its time-delay distance and
We present the lens mass model of the quadruply-imaged gravitationally lensed
quasar WFI2033-4723, and perform a blind cosmographical analysis based on this
system. Our analysis combines (1) time-delay measurements from 14 years of data
obtained by the COSmological MOnitoring of GRAvItational Lenses (COSMOGRAIL)
collaboration, (2) high-resolution imaging,
(3) a measurement of the velocity dispersion of the lens galaxy based on
ESO-MUSE data, and (4) multi-band, wide-field imaging and spectroscopy
characterizing the lens environment. We account for all known sources of
systematics, including the influence of nearby perturbers and complex
line-of-sight structure, as well as the parametrization of the light and mass
profiles of the lensing galaxy. After unblinding, we determine the effective
time-delay distance to be , an average
precision of . This translates to a Hubble constant , assuming a flat CDM
cosmology with a uniform prior on in the range [0.05, 0.5].
This work is part of the Lenses in COSMOGRAIL's Wellspring (H0LiCOW)
collaboration, and the full time-delay cosmography results from a total of six
strongly lensed systems are presented in a companion paper (H0LiCOW XIII).Comment: Version accepted by MNRAS. 29 pages including appendix, 17 figures, 6
tables. arXiv admin note: text overlap with arXiv:1607.0140
The American Astronomical Society, find out more The Institute of Physics, find out more Where Do Quasar Hosts Lie with Respect to the Size–Mass Relation of Galaxies?
The evolution of the galaxy size–mass relation has been a puzzle for over a decade. High-redshift galaxies are significantly more compact than galaxies observed today at an equivalent mass, but how much of this apparent growth is driven by progenitor bias, minor mergers, secular processes, or feedback from active galactic nuclei (AGNs) is unclear. To help disentangle the physical mechanisms at work by addressing the latter, we study the size–Mstellar relation of 32 carefully selected broad-line AGN hosts at 1.2 \u3c z \u3c 1.7 (7.5 \u3c log MBH \u3c 8.5; Lbol/LEdd ≳ 0.1). Using the Hubble Space Telescope with multiband photometry and state-of-the-art modeling techniques, we measure half-light radii while accounting for uncertainties from subtracting bright central point sources. We find AGN hosts to have sizes ranging from ∼1 to 6 kpc at Mstellar ∼ (0.3–1) × 1011 M⊙. Thus, many hosts have intermediate sizes as compared to equal-mass star-forming and quiescent galaxies. While inconsistent with the idea that AGN feedback may induce an increase in galaxy sizes, this finding is consistent with hypotheses in which AGNs preferentially occur in systems with prior concentrated gas reservoirs, or are involved in a secular compaction processes perhaps responsible for building their bulges. If driven by minor mergers that do not grow central black holes as fast as they do bulge-like stellar structures, such a process would explain both the galaxy size–mass relation observed here and the evolution in the black hole–bulge mass relation described in a companion paper
High-resolution imaging follow-up of doubly imaged quasars
We report upon three years of follow-up and confirmation of doubly imaged
quasar lenses through imaging campaigns from 2016-2018 with the Near-Infrared
Camera2 (NIRC2) on the W. M. Keck Observatory. A sample of 57 quasar lens
candidates are imaged in adaptive-optics-assisted or seeing-limited
-band observations. Out of these 57 candidates, 15 are confirmed as
lenses. We form a sample of 20 lenses adding in a number of previously-known
lenses that were imaged with NIRC2 in 2013-14 as part of a pilot study. By
modelling these 20 lenses, we obtain -band relative photometry and
astrometry of the quasar images and the lens galaxy. We also provide the lens
properties and predicted time delays to aid planning of follow-up observations
necessary for various astrophysical applications, e.g., spectroscopic follow-up
to obtain the deflector redshifts for the newly confirmed systems. We compare
the departure of the observed flux ratios from the smooth-model predictions
between doubly and quadruply imaged quasar systems. We find that the departure
is consistent between these two types of lenses if the modelling uncertainty is
comparable.Comment: 11 pages, 8 figures, 5 tables. This version: accepted to MNRA
curatedOvarianData: clinically annotated data for the ovarian cancer transcriptome
This article introduces a manually curated data collection for gene expression meta-analysis of patients with ovarian cancer and software for reproducible preparation of similar databases. This resource provides uniformly prepared microarray data for 2970 patients from 23 studies with curated and documented clinical metadata. It allows users to efficiently identify studies and patient subgroups of interest for analysis and to perform meta-analysis immediately without the challenges posed by harmonizing heterogeneous microarray technologies, study designs, expression data processing methods and clinical data formats. We confirm that the recently proposed biomarker CXCL12 is associated with patient survival, independently of stage and optimal surgical debulking, which was possible only through meta-analysis owing to insufficient sample sizes of the individual studies. The database is implemented as the curatedOvarianData Bioconductor package for the R statistical computing language, providing a comprehensive and flexible resource for clinically oriented investigation of the ovarian cancer transcriptome. The package and pipeline for producing it are available from http://bcb.dfci.harvard.edu/ovariancancer. Database URL: http://bcb.dfci.harvard.edu/ovariancance
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