Reliability in digital systems with asymmetrical failure modes

Reliability schemes in digital systems with asymmetrical failure mode

Combinatorics of bicubic maps with hard particles

We present a purely combinatorial solution of the problem of enumerating planar bicubic maps with hard particles. This is done by use of a bijection with a particular class of blossom trees with particles, obtained by an appropriate cutting of the maps. Although these trees have no simple local characterization, we prove that their enumeration may be performed upon introducing a larger class of "admissible" trees with possibly doubly-occupied edges and summing them with appropriate signed weights. The proof relies on an extension of the cutting procedure allowing for the presence on the maps of special non-sectile edges. The admissible trees are characterized by simple local rules, allowing eventually for an exact enumeration of planar bicubic maps with hard particles. We also discuss generalizations for maps with particles subject to more general exclusion rules and show how to re-derive the enumeration of quartic maps with Ising spins in the present framework of admissible trees. We finally comment on a possible interpretation in terms of branching processes.Comment: 41 pages, 19 figures, tex, lanlmac, hyperbasics, epsf. Introduction and discussion/conclusion extended, minor corrections, references adde

Force distributions in a triangular lattice of rigid bars

We study the uniformly weighted ensemble of force balanced configurations on a triangular network of nontensile contact forces. For periodic boundary conditions corresponding to isotropic compressive stress, we find that the probability distribution for single-contact forces decays faster than exponentially. This super-exponential decay persists in lattices diluted to the rigidity percolation threshold. On the other hand, for anisotropic imposed stresses, a broader tail emerges in the force distribution, becoming a pure exponential in the limit of infinite lattice size and infinitely strong anisotropy.Comment: 11 pages, 17 figures Minor text revisions; added references and acknowledgmen

Classification Tree Models for Predicting Distributions of Michigan Stream Fish from Landscape Variables

Traditionally, fish habitat requirements have been described from local‐scale environmental variables. However, recent studies have shown that studying landscape‐scale processes improves our understanding of what drives species assemblages and distribution patterns across the landscape. Our goal was to learn more about constraints on the distribution of Michigan stream fish by examining landscape‐scale habitat variables. We used classification trees and landscape‐scale habitat variables to create and validate presence‐absence models and relative abundance models for Michigan stream fishes. We developed 93 presence‐absence models that on average were 72% correct in making predictions for an independent data set, and we developed 46 relative abundance models that were 76% correct in making predictions for independent data. The models were used to create statewide predictive distribution and abundance maps that have the potential to be used for a variety of conservation and scientific purposes.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141481/1/tafs0976.pd

Critical collapse of collisionless matter - a numerical investigation

In recent years the threshold of black hole formation in spherically symmetric gravitational collapse has been studied for a variety of matter models. In this paper the corresponding issue is investigated for a matter model significantly different from those considered so far in this context. We study the transition from dispersion to black hole formation in the collapse of collisionless matter when the initial data is scaled. This is done by means of a numerical code similar to those commonly used in plasma physics. The result is that for the initial data for which the solutions were computed, most of the matter falls into the black hole whenever a black hole is formed. This results in a discontinuity in the mass of the black hole at the onset of black hole formation.Comment: 22 pages, LaTeX, 7 figures (ps-files, automatically included using psfig

Complications After Systematic, Random and Image-guided Prostate Biopsy

CONTEXT: Prostate biopsy (PB) represents the gold standard method to confirm the presence of cancer. In addition to traditional random or systematic approaches, a magnetic resonance imaging (MRI)-guided technique has been introduced recently. OBJECTIVE: To perform a systematic review of complications after transrectal ultrasound (TRUS)-guided, transperineal, and MRI-guided PB. EVIDENCE ACQUISITION: We performed a systematic literature search of Web of Science, Embase, and Scopus databases up to October 2015, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Complications and mortality following random, systematic, and image-guided PBs were reviewed. Eighty-five references were included. EVIDENCE SYNTHESIS: The most frequent complication after PB was minor and self-limiting bleeding (hematuria and hematospermia), regardless of the biopsy approach. Occurrence of rectal bleeding was comparable for traditional TRUS-guided and image-guided PBs. Almost 25% of patients experienced lower urinary tract symptoms, but only a few had urinary retention, with higher rates after a transperineal approach. Temporary erectile dysfunction was not negligible, with a return to baseline after 1-6 mo. The incidence of infective complications is increasing, with higher rates among men with medical comorbidities and older age. Transperineal and in-bore MRI-targeted biopsy may reduce the risk of severe infectious complications. Mortality after PB is uncommon, regardless of biopsy technique. CONCLUSIONS: Complications after PB are frequent but often self-limiting. The incidence of hospitalization due to severe infections is continuously increasing. The patient's general health status, risk factors, and likelihood of antimicrobial resistance should be carefully appraised before scheduling a PB. PATIENT SUMMARY: We reviewed the variety and incidence of complications after prostate biopsy. Even if frequent, complications seldom represent a problem for the patient. The most troublesome complications are infections. To minimize this risk, the patient's medical condition should be carefully evaluated before biopsy

Evolutionary Rearrangement of the Amylase Genomic Regions Between Drosophila melanogaster and Drosophila pseudoobscura

Abstract Two Drosophila pseudoobscura genomic clones have sequence similarity to the Drosophila melanogaster amylase region that maps to the 53CD region on the D. melanogaster cytogenetic map. The two clones with similarity to amylase map to sections 73A and 78C of the D. pseudoobscura third chromosome cytogenetic map. The complete sequences of both the 73A and 78C regions were compared to the D. melanogaster genome to determine if the coding region for amylase is present in both regions and to determine the evolutionary mechanism responsible for the observed distribution of the amylase gene or genes. The D. pseudoobscura 73A and 78C linkage groups are conserved with the D. melanogaster 41E and 53CD regions, respectively. The amylase gene, however, has not maintained its conserved linkage between the two species. These data indicate that amylase has moved via a transposition event in the D. melanogaster or D. pseudoobscura lineage. The predicted genes within the 73A and 78C regions show patterns of molecular evolution in synonymous and nonsynonymous sites that are consistent with previous studies of these two species. Conserved synteny occurs when two or more homologous genes are located on the same chromosome in two or more species. Conserved linkage occurs when two or more homologous genes are syntenic and are in the same order on the chromosome in two or more species The third chromosome of Drosophila pseudoobscura is polymorphic for more than 30 gene arrangements that were generated through a series of overlapping paracentric inversions. The a-amylase gene maps to the third chromosome of D. pseudoobscura The 73A region encodes one to three amylase genes There are two broad explanations for why two regions of the third chromosome in D. pseudoobscura are similar to a-amylase. First, one of several a-amylase copies was moved to a new location through a paracentric inversion. The a-amylase gene appears to be capable of repeated duplication events and diversification to new functions This article presents a nucleotide sequence comparison of the 73A and 78C sections of the D. pseudoobscura third chromosome with the conserved linkage groups from the D. melanogaster genome. We will show here that the D. pseudoobscura 73A and 78C linkage groups are conserved with the D. melanogaster 41E and 53CD regions, respectively. The a-amylase gene, however, has not maintained its conserved linkage between the two species. These data suggest that the a-amylase locus has shifted its location via a nonreplicative transposition event in either the D. pseudoobscura or D. melanogaster lineage. Materials and Methods Nucleotide Sequences of the D. pseudoobscura 73A and 78C Regions A 12.6 kb clone that maps to section 78C on the D. pseudoobscura cytogenetic map was digested with the EcoRI restriction endonuclease into four fragments 2.9 kb, 3.8 kb, 1.5 kb, and 4.6 kb in length. These EcoRI fragments were subcloned into the plasmid sequencing vector pWSK29 (Wang and Kushner 1991) using the methods described in Nucleotide Sequence Analysis The 12 kb sequence of the 78C clone was submitted to the GenBank The alignment of sequences was achieved with the MEGALIGN program within the LASERGENE package of DNA sequence analysis software (Madison, WI). Molecular evolutionary sequence analysis was completed with Results Sequence of the 78C Region of D. pseudoobscura The complete sequence of the clone from the D. pseudoobscura 78C region is 12,592 bp in length. There is a slight A/T bias in the sequence, but the difference is not statistically significant from a 50:50 ratio of A/T (50.6%) to G/C (49.6%) with a chi-square goodness-of-fit test (v 2 ¼ 1.64, df ¼ 1, P ¼ .19). GenBank Searches The 12.6 kb sequence from 78C of D. pseudoobscura matched eight D. melanogaster accessions with an E value less than 5 3 10 ÿ9 . All of these accessions map to section 53CD on the D. melanogaster cytogenetic map. Two accessions, AC099032 and AC007520, were genomic sequences from D. melanogaster BAC clones of 163 and 171 kb, respectively. One accession, AE003804, was a 260 kb genomic scaffold assembled in the Drosophila genome project The 12.6 kb sequence from 78C may not provide a complete picture of the degree of conserved linkage between D. melanogaster and D. pseudoobscura because this cloned sequence is relatively small. We used this 12.6 kb sequence to identify a 73.7 kb contig from the D. pseudoobscura whole genome shotgun assembly (Contig1060; Human Genome Sequencing Center 2003). Contig1060 matched 40 D. melanogaster accessions with an E value less than 5 3 10 ÿ9 , including the two BAC clones (AC099032 and AC007520) and the genomic scaffold (AE003804) found with the shorter 78C sequence. This BLAST search also found a match to an additional 158 kb BAC clone (AC005713). Thirteen of the matched accessions were between the cytosolic leucine tRNA genes CR30234 and CR30235 in the 78C region and similar tRNA genes of D. melanogaster at four locations in the genome. The last 23 matched accessions were to short cDNA or genomic clones in the 78C region. The 260 kb genomic scaffold AE003804 was used in all comparisons of the D. pseudoobscura 78C region with the 53CD conserved linkage group of D. melanogaster. The 185 kb sequence (Contig6731_Contig3011) from D. pseudoobscura 73A matched 123 GenBank The D. melanogaster sequence has two a-amylase genes, Amy-p and Amy-d, which are divergently transcribed on the chromosome The CG15605 gene appears to have duplicated in D. pseudoobscura lineage based on dot plot analysis and on translated BLAST searches with the 78C region sequence. This second copy of CG15605 is on the opposite strand from the D. melanogaster homologue of the CG15605 gene, is located near the central microinversion, and appears to be a pseudogene (see below). One might argue that the 12.6 kb sequence from D. pseudoobscura 78C is too small to infer the degree of conserved linkage between the two species. Comparison of Contig1060 from the D. pseudoobscura genome project with the D. melanogaster 53CD region shows that the conserved linkage extends over at least 73.7 kb The conservation of genes between 41E in D. melanogaster and 73A in D. pseudoobscura is shown in Molecular Evolutionary Comparisons of Genes in D. melanogaster and D. pseudoobscura We estimated the frequency of synonymous and nonsynonymous changes between the two species for the genes in the two chromosomal regions A second CG15605 gene segment was identified in a dot plot analysis and appears to be a pseudogene that we designate CG15605w Discussion Rearrangement of the Amylase Region Between D. melanogaster and D. pseudoobscura The 78C region of D. pseudoobscura and the 53CD section of the D. melanogaster genome are conserved linkage groups. The amylase genes, however, are no longer part of this conserved linkage group because the D. pseudoobscura amylase genes are now located within section 73A on the D. pseudoobscura cytogenetic map The comparison of the D. pseudoobscura 73A and the 78C regions with the conserved linkage groups of D. melanogaster suggest that a transposition event rather than a paracentric inversion was responsible for the relocation of the amylase gene. If an inversion event had moved the amylase gene in D. pseudoobscura, then we might expect parts of both the 73A and We were unable to directly infer if the transposition occurred in the D. melanogaster or D. pseudoobscura lineage from the comparison of these two genome regions

Force distribution in a scalar model for non-cohesive granular material

We study a scalar lattice model for inter-grain forces in static, non-cohesive, granular materials, obtaining two primary results. (i) The applied stress as a function of overall strain shows a power law dependence with a nontrivial exponent, which moreover varies with system geometry. (ii) Probability distributions for forces on individual grains appear Gaussian at all stages of compression, showing no evidence of exponential tails. With regard to both results, we identify correlations responsible for deviations from previously suggested theories.Comment: 16 pages, 9 figures, Submitted to PR