The Experts below are selected from a list of 30492 Experts worldwide ranked by ideXlab platform
Albert T Macrander - One of the best experts on this subject based on the ideXlab platform.
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Periodic Variation of stress in sputter deposited si wsi2 multilayers
Applied Physics Letters, 2011Co-Authors: Kimberly Macarthur, Bing Shi, Ray Conley, Albert T MacranderAbstract:A tension increment after sputter deposition of 1 nm of WSi2 onto sputtered Si was observed at low Ar gas pressures. Wafer curvature data on multilayers were found to have a Periodic Variation corresponding to the multilayer period, and this permitted statistical analyses to improve the sensitivity to small stresses. The observation of tension instead of compression in the initial stage of growth is reported, and a model invoking surface rearrangement is invoked. The data also bear on an unusual surface smoothing phenomena for sputtered Si surfaces caused by the sputter deposition of WSi2. We furthermore report that for low Ar pressures the Si layers are the predominant source of built-up stress.
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Periodic Variation of stress in sputter deposited si wsi2 multilayers
arXiv: Materials Science, 2011Co-Authors: Kimberly Macarthur, Bing Shi, Ray Conley, Albert T MacranderAbstract:A tension increment after sputter deposition of 1 nm of WSi2 onto sputtered Si was observed at low Ar gas pressures. Wafer curvature data on multilayers were found to have a Periodic Variation corresponding to the multilayer period, and this permitted statistical analyses to improve the sensitivity to small stresses. The observation of tension instead of compression in the initial stage of growth is new and a model invoking surface rearrangement is invoked. The data also bear on an unusual surface smoothing phenomena for sputtered Si surfaces caused by the sputter deposition of WSi2 . We furthermore report that for low Ar pressures the Si layers are the predominant source of built-up stress.
Vaughn S Cooper - One of the best experts on this subject based on the ideXlab platform.
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Periodic Variation of mutation rates in bacterial genomes associated with replication timing
Mbio, 2018Co-Authors: Marcus M Dillon, Way Sung, Michael Lynch, Vaughn S CooperAbstract:ABSTRACT The causes and consequences of spatiotemporal Variation in mutation rates remain to be explored in nearly all organisms. Here we examine relationships between local mutation rates and replication timing in three bacterial species whose genomes have multiple chromosomes: Vibrio fischeri, Vibrio cholerae, and Burkholderia cenocepacia. Following five mutation accumulation experiments with these bacteria conducted in the near absence of natural selection, the genomes of clones from each lineage were sequenced and analyzed to identify Variation in mutation rates and spectra. In lineages lacking mismatch repair, base substitution mutation rates vary in a mirrored wave-like pattern on opposing replichores of the large chromosomes of V. fischeri and V. cholerae, where concurrently replicated regions experience similar base substitution mutation rates. The base substitution mutation rates on the small chromosome are less variable in both species but occur at similar rates to those in the concurrently replicated regions of the large chromosome. Neither nucleotide composition nor frequency of nucleotide motifs differed among regions experiencing high and low base substitution rates, which along with the inferred ~800-kb wave period suggests that the source of the Periodicity is not sequence specific but rather a systematic process related to the cell cycle. These results support the notion that base substitution mutation rates are likely to vary systematically across many bacterial genomes, which exposes certain genes to elevated deleterious mutational load. IMPORTANCE That mutation rates vary within bacterial genomes is well known, but the detailed study of these biases has been made possible only recently with contemporary sequencing methods. We applied these methods to understand how bacterial genomes with multiple chromosomes, like those of Vibrio and Burkholderia, might experience heterogeneous mutation rates because of their unusual replication and the greater genetic diversity found on smaller chromosomes. This study captured thousands of mutations and revealed wave-like rate Variation that is synchronized with replication timing and not explained by sequence context. The scale of this rate Variation over hundreds of kilobases of DNA strongly suggests that a temporally regulated cellular process may generate wave-like Variation in mutation risk. These findings add to our understanding of how mutation risk is distributed across bacterial and likely also eukaryotic genomes, owing to their highly conserved replication and repair machinery.
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Periodic Variation of mutation rates in bacterial genomes associated with replication timing
bioRxiv, 2017Co-Authors: Marcus M Dillon, Way Sung, Michael Lynch, Vaughn S CooperAbstract:Spontaneous mutation rates may vary within genome regions across the tree of life, but the causes and consequences of this spatiotemporal Variation are uncertain because studies of genome-wide mutation rates with sufficient resolution are rare. Here we examine relationships between local mutation rates and replication timing throughout the genomes of three bacterial species using results from five mutation accumulation (MA) experiments analyzed by whole genome sequencing (WGS). Three MA experiments were carried out with wild-type strains of the species Vibrio fischeri , Vibrio cholerae , and Burkholderia cenocepacia , each of which have multiple chromosomes, while two additional experiments were carried out using mismatch repair-deficient strains of V. fischeri and V. cholerae . We find that in the absence of mismatch repair, base-substitution mutation rates vary in a mirrored wave-like pattern on opposing replichores of the large chromosome of V. fischeri and V. cholerae , where concurrently replicated regions experience similar base-substitution mutation rates. The base-substitution mutation rates on the small chromosome are less variable in both species, but tend to occur at similar rates as the concurrently replicated regions of the large chromosome. We lack a sufficient quantity of base-substitution mutations in the MA-WGS experiments with intact mismatch repair to rigorously evaluate regional Variation in base-substitution mutation rates, although it is possible that a larger collection of base-substitution mutations would reveal rate Periodicity in these experiments. These results support the notion that base-substitution mutation rates are likely to vary systematically across many bacterial genomes, which exposes certain genes to elevated deleterious mutational load.
Kimberly Macarthur - One of the best experts on this subject based on the ideXlab platform.
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Periodic Variation of stress in sputter deposited si wsi2 multilayers
Applied Physics Letters, 2011Co-Authors: Kimberly Macarthur, Bing Shi, Ray Conley, Albert T MacranderAbstract:A tension increment after sputter deposition of 1 nm of WSi2 onto sputtered Si was observed at low Ar gas pressures. Wafer curvature data on multilayers were found to have a Periodic Variation corresponding to the multilayer period, and this permitted statistical analyses to improve the sensitivity to small stresses. The observation of tension instead of compression in the initial stage of growth is reported, and a model invoking surface rearrangement is invoked. The data also bear on an unusual surface smoothing phenomena for sputtered Si surfaces caused by the sputter deposition of WSi2. We furthermore report that for low Ar pressures the Si layers are the predominant source of built-up stress.
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Periodic Variation of stress in sputter deposited si wsi2 multilayers
arXiv: Materials Science, 2011Co-Authors: Kimberly Macarthur, Bing Shi, Ray Conley, Albert T MacranderAbstract:A tension increment after sputter deposition of 1 nm of WSi2 onto sputtered Si was observed at low Ar gas pressures. Wafer curvature data on multilayers were found to have a Periodic Variation corresponding to the multilayer period, and this permitted statistical analyses to improve the sensitivity to small stresses. The observation of tension instead of compression in the initial stage of growth is new and a model invoking surface rearrangement is invoked. The data also bear on an unusual surface smoothing phenomena for sputtered Si surfaces caused by the sputter deposition of WSi2 . We furthermore report that for low Ar pressures the Si layers are the predominant source of built-up stress.
Marcus M Dillon - One of the best experts on this subject based on the ideXlab platform.
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Periodic Variation of mutation rates in bacterial genomes associated with replication timing
Mbio, 2018Co-Authors: Marcus M Dillon, Way Sung, Michael Lynch, Vaughn S CooperAbstract:ABSTRACT The causes and consequences of spatiotemporal Variation in mutation rates remain to be explored in nearly all organisms. Here we examine relationships between local mutation rates and replication timing in three bacterial species whose genomes have multiple chromosomes: Vibrio fischeri, Vibrio cholerae, and Burkholderia cenocepacia. Following five mutation accumulation experiments with these bacteria conducted in the near absence of natural selection, the genomes of clones from each lineage were sequenced and analyzed to identify Variation in mutation rates and spectra. In lineages lacking mismatch repair, base substitution mutation rates vary in a mirrored wave-like pattern on opposing replichores of the large chromosomes of V. fischeri and V. cholerae, where concurrently replicated regions experience similar base substitution mutation rates. The base substitution mutation rates on the small chromosome are less variable in both species but occur at similar rates to those in the concurrently replicated regions of the large chromosome. Neither nucleotide composition nor frequency of nucleotide motifs differed among regions experiencing high and low base substitution rates, which along with the inferred ~800-kb wave period suggests that the source of the Periodicity is not sequence specific but rather a systematic process related to the cell cycle. These results support the notion that base substitution mutation rates are likely to vary systematically across many bacterial genomes, which exposes certain genes to elevated deleterious mutational load. IMPORTANCE That mutation rates vary within bacterial genomes is well known, but the detailed study of these biases has been made possible only recently with contemporary sequencing methods. We applied these methods to understand how bacterial genomes with multiple chromosomes, like those of Vibrio and Burkholderia, might experience heterogeneous mutation rates because of their unusual replication and the greater genetic diversity found on smaller chromosomes. This study captured thousands of mutations and revealed wave-like rate Variation that is synchronized with replication timing and not explained by sequence context. The scale of this rate Variation over hundreds of kilobases of DNA strongly suggests that a temporally regulated cellular process may generate wave-like Variation in mutation risk. These findings add to our understanding of how mutation risk is distributed across bacterial and likely also eukaryotic genomes, owing to their highly conserved replication and repair machinery.
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Periodic Variation of mutation rates in bacterial genomes associated with replication timing
bioRxiv, 2017Co-Authors: Marcus M Dillon, Way Sung, Michael Lynch, Vaughn S CooperAbstract:Spontaneous mutation rates may vary within genome regions across the tree of life, but the causes and consequences of this spatiotemporal Variation are uncertain because studies of genome-wide mutation rates with sufficient resolution are rare. Here we examine relationships between local mutation rates and replication timing throughout the genomes of three bacterial species using results from five mutation accumulation (MA) experiments analyzed by whole genome sequencing (WGS). Three MA experiments were carried out with wild-type strains of the species Vibrio fischeri , Vibrio cholerae , and Burkholderia cenocepacia , each of which have multiple chromosomes, while two additional experiments were carried out using mismatch repair-deficient strains of V. fischeri and V. cholerae . We find that in the absence of mismatch repair, base-substitution mutation rates vary in a mirrored wave-like pattern on opposing replichores of the large chromosome of V. fischeri and V. cholerae , where concurrently replicated regions experience similar base-substitution mutation rates. The base-substitution mutation rates on the small chromosome are less variable in both species, but tend to occur at similar rates as the concurrently replicated regions of the large chromosome. We lack a sufficient quantity of base-substitution mutations in the MA-WGS experiments with intact mismatch repair to rigorously evaluate regional Variation in base-substitution mutation rates, although it is possible that a larger collection of base-substitution mutations would reveal rate Periodicity in these experiments. These results support the notion that base-substitution mutation rates are likely to vary systematically across many bacterial genomes, which exposes certain genes to elevated deleterious mutational load.
Ray Conley - One of the best experts on this subject based on the ideXlab platform.
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Periodic Variation of stress in sputter deposited si wsi2 multilayers
Applied Physics Letters, 2011Co-Authors: Kimberly Macarthur, Bing Shi, Ray Conley, Albert T MacranderAbstract:A tension increment after sputter deposition of 1 nm of WSi2 onto sputtered Si was observed at low Ar gas pressures. Wafer curvature data on multilayers were found to have a Periodic Variation corresponding to the multilayer period, and this permitted statistical analyses to improve the sensitivity to small stresses. The observation of tension instead of compression in the initial stage of growth is reported, and a model invoking surface rearrangement is invoked. The data also bear on an unusual surface smoothing phenomena for sputtered Si surfaces caused by the sputter deposition of WSi2. We furthermore report that for low Ar pressures the Si layers are the predominant source of built-up stress.
-
Periodic Variation of stress in sputter deposited si wsi2 multilayers
arXiv: Materials Science, 2011Co-Authors: Kimberly Macarthur, Bing Shi, Ray Conley, Albert T MacranderAbstract:A tension increment after sputter deposition of 1 nm of WSi2 onto sputtered Si was observed at low Ar gas pressures. Wafer curvature data on multilayers were found to have a Periodic Variation corresponding to the multilayer period, and this permitted statistical analyses to improve the sensitivity to small stresses. The observation of tension instead of compression in the initial stage of growth is new and a model invoking surface rearrangement is invoked. The data also bear on an unusual surface smoothing phenomena for sputtered Si surfaces caused by the sputter deposition of WSi2 . We furthermore report that for low Ar pressures the Si layers are the predominant source of built-up stress.