5,548 research outputs found
Computing and Social Welfare: Minimizing the Societal Harm From Digital Transfor-mation While Preserving the Benefits of Innovation
Social Welfare Computing is an emerging discipline that seeks to direct technology to cause minimum social disruption, and in particular seeks to minimize the harm caused directly by technology. This is markedly different from the better understood strategic use of technology to create value or to address existing social needs. Innovative technologies that are widely adopted created significant value for their users; otherwise they would not be widely adopted. Often the companies that create them obtain new sources of wealth and power, which inevitably lead to new abuses of power and new forms of societal disruption. Societal disruption in turn requires social adaptation, including new regulations to influence the behavior of firms and to define and to protect the rights of an individual in the changed society. Social Welfare Computing seeks to guide social adaptation, combining insights from disciplines as varied as anthropology, business strategy, economics, strategic planning, and law
Protein Evolution within a Structural Space
Understanding of the evolutionary origins of protein structures represents a
key component of the understanding of molecular evolution as a whole. Here we
seek to elucidate how the features of an underlying protein structural "space"
might impact protein structural evolution. We approach this question using
lattice polymers as a completely characterized model of this space. We develop
a measure of structural comparison of lattice structures that is analgous to
the one used to understand structural similarities between real proteins. We
use this measure of structural relatedness to create a graph of lattice
structures and compare this graph (in which nodes are lattice structures and
edges are defined using structural similarity) to the graph obtained for real
protein structures. We find that the graph obtained from all compact lattice
structures exhibits a distribution of structural neighbors per node consistent
with a random graph. We also find that subgraphs of 3500 nodes chosen either at
random or according to physical constraints also represent random graphs. We
develop a divergent evolution model based on the lattice space which produces
graphs that, within certain parameter regimes, recapitulate the scale-free
behavior observed in similar graphs of real protein structures.Comment: 27 pages, 7 figure
Chandra/ACIS Subpixel Event Repositioning. II. Further Refinements and Comparison between Backside and Front-side Illuminated X-ray CCDs
We further investigate subpixel event repositioning (SER) algorithms in
application to Chandra X-ray Observatory (CXO) CCD imaging. SER algorithms have
been applied to backside illuminated (BI) Advanced CCD Imaging Spectrometer
(ACIS) devices, and demonstrate spatial resolution improvements in Chandra/ACIS
observations. Here a new SER algorithm that is charge split dependent is added
to the SER family. We describe the application of SER algorithms to frontside
illuminated (FI) ACIS devices. The results of SER for FI CCDs are compared with
those obtained from SER techniques applied to BI CCD event data. Both simulated
data and Chandra/ACIS observations of the Orion Nebular Cluster were used to
test and evaluate the achievement of the various SER techniques.Comment: 30 pages, 9 figures, submitted to Ap
Room temperature Suzuki coupling of aryl iodides, bromides, and chlorides using a heterogeneous carbon nanotube-palladium nanohybrid catalyst
International audiencePalladium nanoparticles were immobilized on multi-walled carbon nanotubes by a layer-by-layer approach, resulting in a well-defined assembly. The nanohybrid was found effective in promoting Suzuki cross couplings of various halogenated aromatics, including chlorinated ones, with arylboronic acids under sustainable conditions. The heterogeneous catalyst could also easily be recovered from the reaction mixture and reused with no loss of activity over several cycles
Selective conversion of nitroarenes using a carbon nanotube-ruthenium nanohybrid
International audienceRuthenium nanoparticles were assembled on carbon nanotubes and the resulting nanohybrid was used in the hydrazine-mediated catalytic hydrogenation of various nitroarenes, at room temperature. Depending on the solvent, a selective transformation occurred, giving either access to the corresponding aniline or hydroxylamine derivative
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Genomic Profiling Maps Loss of Heterozygosity and Defines the Timing and Stage Dependence of Epigenetic and Genetic Events in Wilms’ Tumors
To understand genetic and epigenetic pathways in Wilms’ tumors, we carried out a genome scan for loss of heterozygosity (LOH) using Affymetrix 10K single nucleotide polymorphism (SNP) chips and supplemented the data with karyotype information. To score loss of imprinting (LOI) of the IGF2 gene, we assessed DNA methylation of the H19 5V differentially methylated region (DMR). Few chromosomal regions other than band 11p13 (WT1) were lost in Wilms’ tumors from Denys-Drash and Wilms’ tumor-aniridia syndromes, whereas sporadic Wilms’ tumors showed LOH of several regions, most frequently 11p15 but also 1p, 4q, 7p, 11q, 14q, 16q, and 17p. LOI was common in the sporadic Wilms’ tumors but absent in the syndromic cases. The SNP chips identified novel centers of LOH in the sporadic tumors, including a 2.4-Mb minimal region on chromosome 4q24-q25. Losses of chromosomes 1p, 14q, 16q, and 17p were more common in tumors presenting at an advanced stage; 11p15 LOH was seen at all stages, whereas LOI was associated with early-stage presentation. Wilms’ tumors with LOI often completely lacked LOH in the genome-wide analysis, and in some tumors with concomitant 16q LOH and LOI, the loss of chromosome 16q was mosaic, whereas the H19 DMR methylation was complete. These findings confirm molecular differences between sporadic and syndromic Wilms’ tumors, define regions of recurrent LOH, and indicate that gain of methylation at the H19 DMR is an early event in Wilms’ tumorigenesis that is independent of chromosomal losses. The data further suggest a biological difference between sporadic Wilms’ tumors with and without LOI
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Genomic surveys by methylation-sensitive SNP analysis identify sequence-dependent allele-specific DNA methylation
Allele-specific DNA methylation (ASM) is a hallmark of imprinted genes, but ASM in the larger nonimprinted fraction of the genome is less well characterized. Using methylation-sensitive SNP analysis (MSNP), we surveyed the human genome at 50K and 250K resolution, identifying ASM as recurrent genotype call conversions from heterozygosity to homozygosity when genomic DNAs were predigested with the methylation-sensitive restriction enzyme HpaII. Using independent assays, we confirmed ASM at 16 SNP-tagged loci distributed across various chromosomes.
At 12 of these loci (75%), the ASM tracked strongly with the sequence of adjacent SNPs. Further analysis showed allele-specific mRNA expression at two loci from this methylation-based screen—the vanin and CYP2A6-CYP2A7 gene clusters—both implicated in traits of medical importance. This recurrent phenomenon of sequence-dependent ASM has practical implications for mapping and interpreting associations of noncoding SNPs and haplotypes with human phenotypes
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