Finite Element Modeling of Wood Bat Profiles for Durability

AbstractThe bats used in Major League Baseball (MLB) are required to be turned from a single piece of wood. Northern white ash had been the wood of choice until the introduction of hard maple in the late 1990s. Since the introduction of maple to the game, there was a perceived increase in the rate of bats to exhibit multiple piece failures (MPF)—both ash and maple. These failures introduced a new aspect to the game that can be a significant factor during play, i.e. pieces of bats going into the field of play, thereby distracting fielders while reacting to the batted ball. Observations of bat breakage in the field and lab testing of bats in controlled conditions have shown the bat durability is a function of wood quality and bat profile. Wood quality is described by the density and the slope of grain of the wood used in the bat. The density and the slope of grain determine the effective strength of the wood. The bat profile is described by the variation in the diameter of the bat along its length. The wood densities and bat profiles which are preferred by players, are typically in direct contradiction with what makes for a durable bat. In this paper, the finite element method is used to develop calibrated models of the breaking of wood bats in controlled lab conditions. The modeling approach is then used to explore how bat profile influences bat durability and what potential changes can be made in bat profile to satisfy player desires while increasing bat durability

Midwest Guardrail System with Round Timber Posts

A modified Midwest Guardrail System (MGS) was developed by using small-diameter round wood posts. The barrier system was configured with three timber species: Douglas fir (DF), ponderosa pine (PP), and southern yellow pine (SYP). Barrier VII computer simulation, combined with cantilever post testing in a rigid sleeve and soil, was used to determine the required post diameter for each species. The recommended nominal sizes were 184 mm (7.25 in.) for DF, 203 mm (8 in.) for PP, and 190 mm (7.5 in.) for SYP. A grading criterion limiting knot size and ring density was established for each species. The recommended knot sizes were limited to 38 mm (1.5 in.) or smaller for DF, 89 mm (3.5 in.) or smaller for PP, and 64 mm (2.5 in.) or smaller for SYP. The minimum ring densities equaled or exceeded 6 rings per inch (rpi) for DF, 6 rpi for PP, and 4 rpi for SYP. Two guardrail systems— one using DF posts and another using PP posts—were crash tested according to the Test Level 3 requirements specified in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. Crash testing was not conducted on the SYP system because of the adequacy of previous testing on 184-mm (7.25-in.) diameter SYP posts in a standard W-beam guardrail system and post design strength comparable to that in the other two species. Both crash tests showed that the modified MGS functioned adequately for both wood species. Three round wood post alternatives were recommended as an acceptable substitute for the standard W152×13.4 (W6×9) steel post used in the MGS

A genome phylogeny for mitochondria among alpha-proteobacteria and a predominantly eubacterial ancestry of yeast nuclear genes

Analyses of 55 individual and 31 concatenated protein data sets encoded in Reclinomonas americana and Marchantia polymorpha mitochondrial genomes revealed that current methods for constructing phylogenetic trees are insufficiently sensitive (or artifact-insensitive) to ascertain the sister of mitochondria among the current sample of eight alpha-proteobacterial genomes using mitochondrially-encoded proteins. However, Rhodospirillum rubrum came as close to mitochondria as any alpha-proteobacterium investigated. This prompted a search for methods to directly compare eukaryotic genomes to their prokaryotic counterparts to investigate the origin of the mitochondrion and its host from the standpoint of nuclear genes. We examined pairwise amino acid sequence identity in comparisons of 6,214 nuclear protein-coding genes from Saccharomyces cerevisiae to 177,117 proteins encoded in sequenced genomes from 45 eubacteria and 15 archaebacteria. The results reveal that approximately 75% of yeast genes having homologues among the present prokaryotic sample share greater amino acid sequence identity to eubacterial than to archaebacterial homologues. At high stringency comparisons, only the eubacterial component of the yeast genome is detectable. Our findings indicate that at the levels of overall amino acid sequence identity and gene content, yeast shares a sister-group relationship with eubacteria, not with archaebacteria, in contrast to the current phylogenetic paradigm based on ribosomal RNA. Among eubacteria and archaebacteria, proteobacterial and methanogen genomes, respectively, shared more similarity with the yeast genome than other prokaryotic genomes surveyed

Complementarity of Private and Correctable Subsystems in Quantum Cryptography and Error Correction

We make an explicit connection between fundamental notions in quantum cryptography and quantum error correction. Error-correcting subsystems (and subspaces) for quantum channels are the key vehicles for contending with noise in physical implementations of quantum information-processing. Private subsystems (and subspaces) for quantum channels play a central role in cryptographic schemes such as quantum secret sharing and private quantum communication. We show that a subsystem is private for a channel precisely when it is correctable for a complementary channel. This result is shown to hold even for approximate notions of private and correctable defined in terms of the diamond norm for superoperators.Comment: 5 pages, 2 figures, preprint versio

Deep Sequencing of the Vaginal Microbiota of Women with HIV

BACKGROUND: Women living with HIV and co-infected with bacterial vaginosis (BV) are at higher risk for transmitting HIV to a partner or newborn. It is poorly understood which bacterial communities constitute BV or the normal vaginal microbiota among this population and how the microbiota associated with BV responds to antibiotic treatment. METHODS AND FINDINGS: The vaginal microbiota of 132 HIV positive Tanzanian women, including 39 who received metronidazole treatment for BV, were profiled using Illumina to sequence the V6 region of the 16S rRNA gene. Of note, Gardnerella vaginalis and Lactobacillus iners were detected in each sample constituting core members of the vaginal microbiota. Eight major clusters were detected with relatively uniform microbiota compositions. Two clusters dominated by L. iners or L. crispatus were strongly associated with a normal microbiota. The L. crispatus dominated microbiota were associated with low pH, but when L. crispatus was not present, a large fraction of L. iners was required to predict a low pH. Four clusters were strongly associated with BV, and were dominated by Prevotella bivia, Lachnospiraceae, or a mixture of different species. Metronidazole treatment reduced the microbial diversity and perturbed the BV-associated microbiota, but rarely resulted in the establishment of a lactobacilli-dominated microbiota. CONCLUSIONS: Illumina based microbial profiling enabled high though-put analyses of microbial samples at a high phylogenetic resolution. The vaginal microbiota among women living with HIV in Sub-Saharan Africa constitutes several profiles associated with a normal microbiota or BV. Recurrence of BV frequently constitutes a different BV-associated profile than before antibiotic treatment