69 research outputs found
The FIRST Bright Quasar Survey. II. 60 Nights and 1200 Spectra Later
We have used the VLA FIRST survey and the APM catalog of the POSS-I plates as
the basis for constructing a new radio-selected sample of optically bright
quasars. This is the first radio-selected sample that is competitive in size
with current optically selected quasar surveys. Using only two basic criteria,
radio-optical positional coincidence and optical morphology, quasars and BL
Lacs can be identified with 60% selection efficiency; the efficiency increases
to 70% for objects fainter than magnitude 17. We show that a more sophisticated
selection scheme can predict with better than 85% reliability which candidates
will turn out to be quasars.
This paper presents the second installment of the FIRST Bright Quasar Survey
with a catalog of 636 quasars distributed over 2682 square degrees. The quasar
sample is characterized and all spectra are displayed. The FBQS detects both
radio-loud and radio-quiet quasars out to a redshift z>3. We find a large
population of objects of intermediate radio-loudness; there is no evidence in
our sample for a bimodal distribution of radio characteristics. The sample
includes ~29 broad absorption line quasars, both high and low ionization, and a
number of new objects with remarkable optical spectra.Comment: 41 pages plus 39 gifs which contain all quasar spectra. Accepted for
publication in the Astrophysical Journal Supplement Serie
A Multifunctional, Charge-Neutral, Chiral Octahedral M12 L12 Cage.
peer reviewedA chiral, octahedral M12 L12 cage, which is charge neutral and contains an internal void of about 2000 Å3 , is reported. The cage was synthesised as an enantiopure complex by virtue of amino-acid-based dicarboxylate ligands, which assemble around copper paddlewheels at the vertices of the octahedron. The cage persists in solution with retention of the fluorescence properties of the parent acid. The solid-state structure contains large pores both within and between the cages, and displays permanent porosity for the sorption of gases with retention of crystallinity. Initial tests show some enantioselectivity of the cage towards guests in solution
Campaign Finance Reform: The Unfinished Agenda
In 1974, following the Watergate scandal, Congress enacted major campaign finance reform legislation. The legislation created a revolutionary new public financing system for our presidential campaigns, but it left congressional campaigns to be financed totally by private money. The presidential public financing system has worked well. Despite some incremental problems, the system has accomplished its basic goal of allowing individuals to run for the presidency without becoming dependent on their financial backers. The system for financing congressional cam paigns, on the other hand, is out of control and in need of fundamental reform. The inappropriate role of special interest political action commit tees (PACs) in influencing congressional elections and congressional decisions is the single biggest problem facing the political process. Congress needs to complete the unfinished campaign finance reform agenda of the 1970s by enacting public financing for congressional campaigns and establishing new restrictions on the total amount that PACs may give to a congressional candidate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67356/2/10.1177_000271628648600107.pd
In Search of an Uncultured Human-Associated TM7 Bacterium in the Environment
We have identified an environmental bacterium in the Candidate Division TM7 with ≥98.5% 16S rDNA gene homology to a group of TM7 bacteria associated with the human oral cavity and skin. The environmental TM7 bacterium (referred to as TM7a-like) was readily detectable in wastewater with molecular techniques over two years of sampling. We present the first images of TM7a-like cells through FISH technique and the first images of any TM7 as viable cells through the STARFISH technique. In situ quantification showed TM7 concentration in wastewater up to five times greater than in human oral sites. We speculate that upon further characterization of the physiology and genetics of the TM7a-like bacterium from environmental sources and confirmation of its genomic identity to human-associated counterparts it will serve as model organisms to better understand its role in human health. The approach proposed circumvents difficulties imposed by sampling humans, provides an alternative strategy to characterizing some diseases of unknown etiology, and renders a much needed understanding of the ecophysiological role hundreds of unique Bacteria and Archaea strains play in mixed microbial communities
Integrated genomic characterization of pancreatic ductal adenocarcinoma
We performed integrated genomic, transcriptomic, and proteomic profiling of 150 pancreatic ductal adenocarcinoma (PDAC) specimens, including samples with characteristic low neoplastic cellularity. Deep whole-exome sequencing revealed recurrent somatic mutations in KRAS, TP53, CDKN2A, SMAD4, RNF43, ARID1A, TGFβR2, GNAS, RREB1, and PBRM1. KRAS wild-type tumors harbored alterations in other oncogenic drivers, including GNAS, BRAF, CTNNB1, and additional RAS pathway genes. A subset of tumors harbored multiple KRAS mutations, with some showing evidence of biallelic mutations. Protein profiling identified a favorable prognosis subset with low epithelial-mesenchymal transition and high MTOR pathway scores. Associations of non-coding RNAs with tumor-specific mRNA subtypes were also identified. Our integrated multi-platform analysis reveals a complex molecular landscape of PDAC and provides a roadmap for precision medicine
Female chromosome X mosaicism is age-related and preferentially affects the inactivated X chromosome
To investigate large structural clonal mosaicism of chromosome X, we analysed the SNP microarray intensity data of 38,303 women from cancer genome-wide association studies (20,878 cases and 17,425 controls) and detected 124 mosaic X events >2 Mb in 97 (0.25%) women. Here we show rates for X-chromosome mosaicism are four times higher than mean autosomal rates; X mosaic events more often include the entire chromosome and participants with X events more likely harbour autosomal mosaic events. X mosaicism frequency increases with age (0.11% in 50-year olds; 0.45% in 75-year olds), as reported for Y and autosomes. Methylation array analyses of 33 women with X mosaicism indicate events preferentially involve the inactive X chromosome. Our results provide further evidence that the sex chromosomes undergo mosaic events more frequently than autosomes, which could have implications for understanding the underlying mechanisms of mosaic events and their possible contribution to risk for chronic diseases
Female chromosome X mosaicism is age-related and preferentially affects the inactivated X chromosome
To investigate large structural clonal mosaicism of chromosome X, we analysed the SNP
microarray intensity data of 38,303 women from cancer genome-wide association studies
(20,878 cases and 17,425 controls) and detected 124 mosaic X events42Mb in 97 (0.25%)
women. Here we show rates for X-chromosome mosaicism are four times higher than mean
autosomal rates; X mosaic events more often include the entire chromosome and participants
with X events more likely harbour autosomal mosaic events. X mosaicism frequency
increases with age (0.11% in 50-year olds; 0.45% in 75-year olds), as reported for Y and
autosomes. Methylation array analyses of 33 women with X mosaicism indicate events
preferentially involve the inactive X chromosome. Our results provide further evidence that
the sex chromosomes undergo mosaic events more frequently than autosomes, which could
have implications for understanding the underlying mechanisms of mosaic events and their
possible contribution to risk for chronic diseases
Modulating Porosity through Conformer-Dependent Hydrogen Bonding in Copper(II) Coordination Polymers
A new divergent ligand, <i>N</i>,<i>N</i>′-bis(4-carboxyphenylmethylene)ethane-1,2-diamine
(<b>H</b><sub><b>4</b></sub><b>L1</b>), has been
prepared in high yield and used to generate two copper(II) coordination
polymer materials, <i>poly-</i>[Cu(<b>H</b><sub><b>2</b></sub><b>L1</b>)(OH<sub>2</sub>)]·H<sub>2</sub>O (<b>1</b>) and <i>poly</i>-[Cu(<b>H</b><sub><b>2</b></sub><b>L1</b>)(OH<sub>2</sub>)]·H<sub>2</sub>O·DMF (<b>2</b>). Both networks possess (4,4) sheet
topologies and have almost identical compositions and coordination
modes. The only major difference between the compounds lies with the
conformation of the chelating ethylenediamine cores; compound <b>1</b> adopts a <i>trans</i>-(<i>R</i>,<i>R</i>/<i>S</i>,<i>S</i>) conformation, while
compound <b>2</b> exhibits a <i>cis</i>-(<i>R</i>,<i>S</i>) conformation. This seemingly small difference
arising from variation in synthetic conditions influences the extended
structures of each network through hydrogen bonding interactions,
resulting in the formation of a close packed 2-fold 2D → 2D
parallel interpenetrated network for <b>1</b>, while the extended,
non-interpenetrated structure of <b>2</b> contains aligned one-dimensional
solvent channels. After solvent exchange and evacuation, compound <b>2</b> was found to adsorb approximately 35 cm<sup>3</sup>(STP)/g
of CO<sub>2</sub> at atmospheric pressure at 273 K, with a zero-loading
enthalpy of adsorption of −33 kJ/mol, while adsorbing only
minimal quantities of N<sub>2</sub>. These findings are a rare example
of conformer-dependent porosity in otherwise geometrically similar
frameworks and highlight the importance of understanding weak and
fluxional secondary interactions in framework and ligand design
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