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Search Results: 1 - 10 of 234680 matches for " Christopher R. Bowen "
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Preliminary Study of Optimum Piezoelectric Cross-Ply Composites for Energy Harvesting
David N. Betts,H. Alicia Kim,Christopher R. Bowen
Smart Materials Research , 2012, DOI: 10.1155/2012/621364
Abstract: Energy harvesting devices based on a piezoelectric material attached to asymmetric bistable laminate plates have been shown to exhibit high levels of power extraction over a wide range of frequencies. This paper optimizes for the design of bistable composites combined with piezoelectrics for energy harvesting applications. The electrical energy generated during state-change, or “snap-through,” is maximized through variation in ply thicknesses and rectangular laminate edge lengths. The design is constrained by a bistability constraint and limits on both the magnitude of deflection and the force required for the reversible actuation. Optimum solutions are obtained for differing numbers of plies and the numerical investigation results are discussed. 1. Introduction Energy harvesting which converts ambient mechanical vibrations into electrical energy is an area of considerable research interest and has received extensive attention in the past decade. A variety of methods have been considered including inductive, capacitive, and piezoelectric materials [1–3]. In many cases harvesting devices have been designed to operate at resonance to optimize the power generation, for example, simple linear cantilever beam configurations. However, ambient vibrations generally exhibit multiple time-dependent frequencies which can include components at relatively low frequencies. This can make typical linear systems inefficient or unsuitable; particularly if the resonant frequency of the device is higher than the frequency range of the vibrations it is attempting to harvest. In order to improve the efficiency of vibrational energy harvesters, recent work has focused on exploiting nonlinearity for broadband energy harvesting. Encouraging results [2] have been obtained using nonlinear or bistable cantilevered beams. Stanton et al. [2] modeled and experimentally validated a non-linear energy harvester using a piezoelectric cantilever. An end magnet on the oscillating cantilever interacts with oppositely poled stationary magnets, which induces softening or hardening into the system and allows the resonance frequency to be tuned. This technique was shown to outperform linear systems when excited by varying frequencies. However, such a system would require an obtrusive arrangement of external magnets and could generate unwanted electromagnetic fields. An alternative method has been recently found where a piezoelectric element is attached to bistable laminate plates with 2 plies and a total ( ) layup of to induce large amplitude oscillations [3]. Such harvesting structures have
High Connectivity in the Deepwater Snapper Pristipomoides filamentosus (Lutjanidae) across the Indo-Pacific with Isolation of the Hawaiian Archipelago
Michelle R. Gaither, Shelley A. Jones, Christopher Kelley, Stephen J. Newman, Laurie Sorenson, Brian W. Bowen
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0028913
Abstract: In the tropical Indo-Pacific, most phylogeographic studies have focused on the shallow-water taxa that inhabit reefs to approximately 30 m depth. Little is known about the large predatory fishes, primarily snappers (subfamily Etelinae) and groupers (subfamily Epinephelinae) that occur at 100–400 m. These long-lived, slow-growing species support fisheries across the Indo-Pacific, yet no comprehensive genetic surveys within this group have been conducted. Here we contribute the first range-wide survey of a deepwater Indo-Pacific snapper, Pristipomoides filamentosus, with special focus on Hawai'i. We applied mtDNA cytochrome b and 11 microsatellite loci to 26 samples (N = 1,222) collected across 17,000 km from Hawai'i to the western Indian Ocean. Results indicate that P. filamentosus is a highly dispersive species with low but significant population structure (mtDNA ΦST = 0.029, microsatellite FST = 0.029) due entirely to the isolation of Hawai'i. No population structure was detected across 14,000 km of the Indo-Pacific from Tonga in the Central Pacific to the Seychelles in the western Indian Ocean, a pattern rarely observed in reef species. Despite a long pelagic phase (60–180 days), interisland dispersal as adults, and extensive gene flow across the Indo-Pacific, P. filamentosus is unable to maintain population connectivity with Hawai'i. Coalescent analyses indicate that P. filamentosus may have colonized Hawai'i 26 K–52 K y ago against prevailing currents, with dispersal away from Hawai'i dominating migration estimates. P. filamentosus harbors low genetic diversity in Hawai'i, a common pattern in marine fishes, and our data indicate a single archipelago-wide stock. However, like the Hawaiian Grouper, Hyporthodus quernus, this snapper had several significant pairwise comparisons (FST) clustered around the middle of the archipelago (St. Rogatien, Brooks Banks, Gardner) indicating that this region may be isolated or (more likely) receives input from Johnston Atoll to the south.
Phylogeographic Analyses of Submesophotic Snappers Etelis coruscans and Etelis “marshi” (Family Lutjanidae) Reveal Concordant Genetic Structure across the Hawaiian Archipelago
Kimberly R. Andrews, Virginia N. Moriwake, Christie Wilcox, E. Gordon Grau, Christopher Kelley, Richard L. Pyle, Brian W. Bowen
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091665
Abstract: The Hawaiian Archipelago has become a natural laboratory for understanding genetic connectivity in marine organisms as a result of the large number of population genetics studies that have been conducted across this island chain for a wide taxonomic range of organisms. However, population genetic studies have been conducted for only two species occurring in the mesophotic or submesophotic zones (30+m) in this archipelago. To gain a greater understanding of genetic connectivity in these deepwater habitats, we investigated the genetic structure of two submesophotic fish species (occurring ~200–360 m) in this archipelago. We surveyed 16 locations across the archipelago for submesophotic snappers Etelis coruscans (N = 787) and E. “marshi” (formerly E. carbunculus; N = 770) with 436–490 bp of mtDNA cytochrome b and 10–11 microsatellite loci. Phylogeographic analyses reveal no geographic structuring of mtDNA lineages and recent coalescence times that are typical of shallow reef fauna. Population genetic analyses reveal no overall structure across most of the archipelago, a pattern also typical of dispersive shallow fishes. However some sites in the mid-archipelago (Raita Bank to French Frigate Shoals) had significant population differentiation. This pattern of no structure between ends of the Hawaiian range, and significant structure in the middle, was previously observed in a submesophotic snapper (Pristipomoides filamentosus) and a submesophotic grouper (Hyporthodus quernus). Three of these four species also have elevated genetic diversity in the mid-archipelago. Biophysical larval dispersal models from previous studies indicate that this elevated diversity may result from larval supplement from Johnston Atoll, ~800 km southwest of Hawaii. In this case the boundaries of stocks for fishery management cannot be defined simply in terms of geography, and fishery management in Hawaii may need to incorporate external larval supply into management plans.
Life after Addiction—Post-Operative Pain Management in an Obstetrical Patient on Long-Term Buprenorphine Therapy  [PDF]
Kelly R Bowen, Jonathan D Baum
Open Journal of Obstetrics and Gynecology (OJOG) , 2017, DOI: 10.4236/ojog.2017.79096
Abstract: A G6P2032 female, prior cesarean x3 with history of opioid addiction maintained on buprenorphine presented for scheduled repeat cesarean section. Pre-operatively, her maintenance dose of medication was held secondary to concerns for partial agonist effect. Post-operative pain control was suboptimal with the patient ultimately proceeding to withdrawal. Doses of hydromorphone were titrated to 10 mg every 3 hours to avoid further withdrawal. Review of expert opinion after discharge recommended against holding buprenorphine therapy in the post-operative period. Pain management options include maintenance therapy with additional doses of opioid and non-opioid pain relieving medications.
The Hidden Mass and Large Spatial Extent of a Poststarburst Galaxy Outflow
Todd M. Tripp,Joseph D. Meiring,J. Xavier Prochaska,Christopher N. A. Willmer,J. Christopher Howk,Jessica K. Werk,Edward B. Jenkins,David V. Bowen,Nicolas Lehner,Kenneth R. Sembach,Christopher Thom,Jason Tumlinson
Physics , 2011, DOI: 10.1126/science.1209850
Abstract: Outflowing winds of multiphase plasma have been proposed to regulate the buildup of galaxies, but key aspects of these outflows have not been probed with observations. Using ultraviolet absorption spectroscopy, we show that "warm-hot" plasma at 10^{5.5} K contains 10-150 times more mass than the cold gas in a poststarburst galaxy wind. This wind extends to distances >68 kiloparsecs, and at least some portion of it will escape. Moreover, the kinematical correlation of the cold and warm-hot phases indicates that the warm-hot plasma is related to the interaction of the cold matter with a hotter (unseen) phase at >>10^{6} K. Such multiphase winds can remove substantial masses and alter the evolution of poststarburst galaxies.
An Ileal Crohn's Disease Gene Signature Based on Whole Human Genome Expression Profiles of Disease Unaffected Ileal Mucosal Biopsies
Tianyi Zhang, Bowen Song, Wei Zhu, Xiao Xu, Qing Qing Gong, Christopher Morando, Themistocles Dassopoulos, Rodney D. Newberry, Steven R. Hunt, Ellen Li
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037139
Abstract: Previous genome-wide expression studies have highlighted distinct gene expression patterns in inflammatory bowel disease (IBD) compared to control samples, but the interpretation of these studies has been limited by sample heterogeneity with respect to disease phenotype, disease activity, and anatomic sites. To further improve molecular classification of inflammatory bowel disease phenotypes we focused on a single anatomic site, the disease unaffected proximal ileal margin of resected ileum, and three phenotypes that were unlikely to overlap: ileal Crohn's disease (ileal CD), ulcerative colitis (UC), and control patients without IBD. Whole human genome (Agilent) expression profiling was conducted on two independent sets of disease-unaffected ileal samples collected from the proximal margin of resected ileum. Set 1 (47 ileal CD, 27 UC, and 25 Control non-IBD patients) was used as the training set and Set 2 was subsequently collected as an independent test set (10 ileal CD, 10 UC, and 10 control non-IBD patients). We compared the 17 gene signatures selected by four different feature-selection methods to distinguish ileal CD phenotype with non-CD phenotype. The four methods yielded different but overlapping solutions that were highly discriminating. All four of these methods selected FOLH1 as a common feature. This gene is an established biomarker for prostate cancer, but has not previously been associated with Crohn's disease. Immunohistochemical staining confirmed increased expression of FOLH1 in the ileal epithelium. These results provide evidence for convergent molecular abnormalities in the macroscopically disease unaffected proximal margin of resected ileum from ileal CD subjects.
A Brassica Exon Array for Whole-Transcript Gene Expression Profiling
Christopher G. Love,Neil S. Graham,Seosamh ó Lochlainn,Helen C. Bowen,Sean T. May,Philip J. White,Martin R. Broadley,John P. Hammond,Graham J. King
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0012812
Abstract: Affymetrix GeneChip? arrays are used widely to study transcriptional changes in response to developmental and environmental stimuli. GeneChip? arrays comprise multiple 25-mer oligonucleotide probes per gene and retain certain advantages over direct sequencing. For plants, there are several public GeneChip? arrays whose probes are localised primarily in 3′ exons. Plant whole-transcript (WT) GeneChip? arrays are not yet publicly available, although WT resolution is needed to study complex crop genomes such as Brassica, which are typified by segmental duplications containing paralogous genes and/or allopolyploidy. Available sequence data were sampled from the Brassica A and C genomes, and 142,997 gene models identified. The assembled gene models were then used to establish a comprehensive public WT exon array for transcriptomics studies. The Affymetrix GeneChip? Brassica Exon 1.0 ST Array is a 5 μM feature size array, containing 2.4 million 25-base oligonucleotide probes representing 135,201 gene models, with 15 probes per gene distributed among exons. Discrimination of the gene models was based on an E-value cut-off of 1E?5, with ≤98% sequence identity. The 135 k Brassica Exon Array was validated by quantifying transcriptome differences between leaf and root tissue from a reference Brassica rapa line (R-o-18), and categorisation by Gene Ontologies (GO) based on gene orthology with Arabidopsis thaliana. Technical validation involved comparison of the exon array with a 60-mer array platform using the same starting RNA samples. The 135 k Brassica Exon Array is a robust platform. All data relating to the array design and probe identities are available in the public domain and are curated within the BrassEnsembl genome viewer at http://www.brassica.info/BrassEnsembl/in?dex.html.
Intellectual Pilgrimages and Local Norms in Fashioning Indonesian Islam Pélerinages intellectuels et normes locales dans la mise en forme de l’islam indonésien
John R. Bowen
Revue des Mondes Musulmans et de la Méditerranée , 2011, DOI: 10.4000/remmm.5323
Abstract: Depuis le début de la présence islamique dans l’archipel indonésien, les musulmans privilégient les rapports avec ce qu’ils voient comme les centres intellectuels de l’étude de l’islam, par les communications qu’ils entretiennent avec eux et leurs voyages. Je décris quelques-uns des effets de ces pèlerinages intellectuels sur les débats concernant l’Islam et tout particulièrement la loi Islamique en Indonésie. L’influence du niveau global sur le local ne se résume pas à une simple transposition de catégories importées. En effet, les penseurs et acteurs dans le domaine du droit justifient l’application de la loi islamique en affirmant ses racines dans les valeurs et les traditions locales. Muslims living in the Indonesian archipelago have long placed considerable importance on their travels to and communications with what they saw as intellectual centers for the study of Islam. I trace some of the effects of these “intellectual pilgrimages” to Mecca, Cairo, and elsewhere on Indonesian deliberations about Islam, particularly concerning Islamic law. I argue that these references to abroad do not flatten out global Islamic discourse, but often stimulate an attention to local norms, or an effort to justify Islamic law as stemming from local traditions.
CD200R1 Supports HSV-1 Viral Replication and Licenses Pro-Inflammatory Signaling Functions of TLR2
Roy J. Soberman, Christopher R. MacKay, Christine A. Vaine, Glennice Bowen Ryan, Anna M. Cerny, Mikayla R. Thompson, Boris Nikolic, Valeria Primo, Peter Christmas, Paul Sheiffele, Lisa Aronov, David M. Knipe, Evelyn A. Kurt-Jones
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047740
Abstract: The CD200R1:CD200 axis is traditionally considered to limit tissue inflammation by down-regulating pro-inflammatory signaling in myeloid cells bearing the receptor. We generated CD200R1?/? mice and employed them to explore both the role of CD200R1 in regulating macrophage signaling via TLR2 as well as the host response to an in vivo, TLR2-dependent model, herpes simplex virus 1 (HSV-1) infection. CD200R1?/? peritoneal macrophages demonstrated a 70–75% decrease in the generation of IL-6 and CCL5 (Rantes) in response to the TLR2 agonist Pam2CSK4 and to HSV-1. CD200R1?/? macrophages could neither up-regulate the expression of TLR2, nor assemble a functional inflammasome in response to HSV-1. CD200R1?/? mice were protected from HSV-1 infection and exhibited dysfunctional TLR2 signaling. Finally, both CD200R1?/? mice and CD200R1?/? fibroblasts and macrophages showed a markedly reduced ability to support HSV-1 replication. In summary, our data demonstrate an unanticipated and novel requirement for CD200R1 in “licensing” pro-inflammatory functions of TLR2 and in limiting viral replication that are supported by ex vivo and in vivo evidence.
The shape of a small universe: signatures in the cosmic microwave background
R. Bowen,P. G. Ferreira
Physics , 2002, DOI: 10.1103/PhysRevD.66.041302
Abstract: We consider the most general parametrization of flat topologically compact universes, complementing the work of Scannapieco, Levin and Silk to include non-trivial shapes. We find that modifications in shape of the fundamental domain will lead to distinct signatures in the anisotropy of the cosmic microwave radiation. We make a preliminary assessment of the effect on three statistics: the angular power spectrum, the distribution of identified ``circles'' on the surface of last scattering and the correlation function of antipodal points.
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