143 research outputs found
Identification of Outflows and Candidate Dual Active Galactic Nuclei in SDSS Quasars at z=0.8-1.6
We present a sample of 131 quasars from the Sloan Digital Sky Survey at
redshifts 0.8<z<1.6 with double peaks in either of the high-ionization narrow
emission lines [NeV]3426 or [NeIII]3869. These sources were selected with the
intention of identifying high-redshift analogs of the z<0.8 active galactic
nuclei (AGN) with double-peaked [OIII]5007 lines, which might represent AGN
outflows or dual AGN. Lines of high-ionization potential are believed to
originate in the inner, highly photoionized portion of the narrow line region
(NLR), and we exploit this assumption to investigate the possible kinematic
origins of the double-peaked lines. For comparison, we measure the [NeV]3426
and [NeIII]3869 double peaks in low-redshift (z<0.8) [OIII]-selected sources.
We find that [NeV]3426 and [NeIII]3869 show a correlation between
line-splitting and line-width similar to that of [OIII]5007 in other studies;
and the velocity-splittings are correlated with the quasar Eddington ratio.
These results suggest an outflow origin for at least a subset of the
double-peaks, allowing us to study the high-ionization gas kinematics around
quasars. However, we find that a non-neligible fraction of our sample show no
evidence for an ionization stratification. For these sources, the outflow
scenario is less compelling, leaving the dual AGN scenario as a viable
possibility. Finally, we find that our sample shows an anti-correlation between
the velocity-offset ratio and luminosity ratio of the components, which is a
potential dynamical argument for the presence of dual AGN. Therefore, this
study serves as a first attempt at extending the selection of candidate dual
AGN to higher redshifts.Comment: 19 pages, 12 figures, accepted for publication in The Astrophysical
Journa
Gene-specific FACS sorting method for target selection in high-throughput amplicon sequencing
Background In addition to shotgun sequencing, next generation sequencing has been shown to be suitable for deep sequencing of many specific PCR-amplified target genes in parallel. However, unspecific product formation is a common problem in amplicon sequencing since these fragments are difficult to fully remove by gel purification, and their presence inevitably reduces the number of mappable sequence reads that can be obtained in each sequencing run. Results We have used a novel flow cytometric sorting approach to specifically enrich Roche/454 DNA Capture beads carrying target DNA sequences on their surface, and reject beads carrying unspecific sequences. This procedure gives a nearly three-fold increase in the fraction of informative sequences obtained. Presented results also show that there are no significant differences in the distribution or presence of different genotypes between a FACS-enriched sample and a standard-enriched control sample. Conclusions Target-specific FACS enrichment prior to Roche/454 sequencing provides a quick, inexpensive way of increasing the amount of high quality data obtained in a single sequencing run, without introducing any sequence bias.QC 2010090
A Comparative Study of Contrasting Machine Learning Frameworks Applied to RANS Modeling of Jets in Crossflow
Classical RANS turbulence models have known deficiencies when applied to jets in crossflow. Identifying the linear Boussinesq stress-strain hypothesis as a major contribution to erroneous prediction, we consider and contrast two machine learning frameworks for turbulence model development. Gene Expression Programming, an evolutionary algorithm that employs a survival of the fittest analogy, and a Deep Neural Network, based on neurological processing, add non-linear terms to the stress-strain relationship. The results are Explicit Algebraic Stress Model-like closures. High fidelity data from an inline jet in crossflow study is used to regress new closures. These models are then tested on a skewed jet to ascertain their predictive efficacy. For both methodologies, a vast improvement over the linear relationship is observed
TR-2002004: On the Effectiveness of Tangible Interfaces in Collaborative Learning Environments
Exome sequencing of contralateral breast cancer identifies metastatic disease
Women with contralateral breast cancer (CBC) have significantly worse prognosis
compared to women with unilateral cancer. A possible explanation of the poor
prognosis of patients with CBC is that in a subset of patients, the second cancer
is not a new primary tumor but a metastasis of the first cancer that has
potentially obtained aggressive characteristics through selection of treatment.
Exome and whole-genome sequencing of solid tumors has previously been used to
investigate the clonal relationship between primary tumors and metastases in
several diseases. In order to assess the relationship between the first and the
second cancer, we performed exome sequencing to identify somatic mutations in
both first and second cancers, and compared paired normal tissue of 25 patients
with metachronous CBC. For three patients, we identified shared somatic mutations
indicating a common clonal origin thereby demonstrating that the second tumor is
a metastasis of the first cancer, rather than a new primary cancer. Accordingly,
these patients all developed distant metastasis within 3 years of the second
diagnosis, compared with 7 out of 22 patients with non-shared somatic profiles.
Genomic profiling of both tumors help the clinicians distinguish between true
CBCs and subsequent metastasesVetenskapsrådetForteAccepte
Flow cytometry for enrichment and titration in massively parallel DNA sequencing
Massively parallel DNA sequencing is revolutionizing genomics research throughout the life sciences. However, the reagent costs and labor requirements in current sequencing protocols are still substantial, although improvements are continuously being made. Here, we demonstrate an effective alternative to existing sample titration protocols for the Roche/454 system using Fluorescence Activated Cell Sorting (FACS) technology to determine the optimal DNA-to-bead ratio prior to large-scale sequencing. Our method, which eliminates the need for the costly pilot sequencing of samples during titration is capable of rapidly providing accurate DNA-to-bead ratios that are not biased by the quantification and sedimentation steps included in current protocols. Moreover, we demonstrate that FACS sorting can be readily used to highly enrich fractions of beads carrying template DNA, with near total elimination of empty beads and no downstream sacrifice of DNA sequencing quality. Automated enrichment by FACS is a simple approach to obtain pure samples for bead-based sequencing systems, and offers an efficient, low-cost alternative to current enrichment protocols
Space and practices:Engagement of children under 3 with tablets and televisions in homes in Spain, Sweden and England
Young children’s engagements with digital technologies form part of their emergent everyday literacy practices. The study reported here derives from the pan-European study ‘A Day in the Digital Lives of Children aged 0-3’. The methodology was centred on the videoing of an entire day’s experiences of a child aged under 3, together with a reflective interview with the parents and inventories related to digital access, skills and activities of the child. In this paper, we look at three children in Spain, Sweden and England, respectively. We examine our data through three prisms. (1) Spatio-temporal: We consider the children’s engagements in terms of their appropriation of space, in relationships with others in the home and the intimate geographies of young children’s digital literacies. (2) Parental discourse: We use the tensions and contradictions for families framework to examine the selection and monitoring of digital literacies. (3) Practice: Drawing on the first two prisms, we zoom into how children engage with tablet devices and television. Our research demonstrates richness, diversity and agency in these young children’s practices with technologies. We propose the concept of living-room assemblage as an analytical metaphor to understand the macrohabitats of young children’s digital literacies and practices, which emerge as multi-layered, creative and co-occurring with other family activities.Our analysis also explores the challenges presented to parents and the ways in which they navigate tensions and contradictions in their media and digital environments, which are condensed in family practices and discourses around tablets and television
On the equivalence of the Einstein-Hilbert and the Einstein-Palatini formulations of general relativity for an arbitrary connection
In the framework of the Einstein-Palatini formalism, even though the
projective transformation connecting the arbitrary connection with the Levi
Civita connection has been floating in the literature for a long time and
perhaps the result was implicitly known in the affine gravity community, yet as
far as we know Julia and Silva were the first to realise its gauge character.
We rederive this result by using the Rosenfeld-Dirac-Bergmann approach to
constrained Hamiltonian systems and do a comprehensive self contained analysis
establishing the equivalence of the Einstein-Palatini and the metric
formulations without having to impose the gauge choice that the connection is
symmetric. We also make contact with the the Einstein-Cartan theory when the
matter Lagrangian has fermions.Comment: 18 pages. Slight change in the title and wording of some sections to
emphasize the main results. References added. Matches published versio
Neurology
Contains reports on six research projects.Public Health Service (B-3055, B-3090)United States Air Force (AF33(616)-7282, AF49(638)-1130)United States Navy, Office of Naval Research (Nonr-609(39))United States Army Chemical Corps (DA-18-108-405-Cml-942)National Science Foundation (Grant G-16526
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