794 research outputs found

    What can seabirds tell us about the tide?

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    Small global positioning system (GPS) trackers are now routinely used to study the movement and behaviour of birds at sea. If the birds rest on the water they become “drifters of opportunity” and can be used to give information about surface currents. In this paper, we use a small data set from satellite-tracked razorbills (Alca torda) in the Irish Sea to test the potential of this idea for measuring tidal currents. Razorbills regularly rest on the sea overnight and their tracks at this time are consistent with their drifting with the tidal flows and changing direction as the flood turns to ebb and vice versa. Data from 4 years (2011–2014) have been binned in a geographical grid and analysed to give the variation of current over a mean tidal cycle in each grid element. A map of maximum current speed is consistent with a numerical model of the tidal currents in the region. The root mean square difference between observed maximum speed and that predicted by the model is 0.15&thinsp;m&thinsp;s−1, about 15&thinsp;% of typical current speeds in the area. The divergence between bird-track speed and model prediction increases in regions of the fastest tidal currents. The method clearly has its limitations, but the results of this study show that tagged birds resting on the sea have potential to provide relatively inexpensive quantitative information about surface tidal currents over an extended geographical area.</p

    Wrinkle initiation and development in heated webs on drums

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    Wrinkles often occur in webs heated on drums and rollers. Anecdotal evidence from vacuum metalizers suggests that wrinkles are initiated by small grit particles or surface imperfections that lift the web off the drum. An elliptical patch of web centered on the dirt particle is lifted off the drum against the tension pressure acting to restore contact. A numerical "tent model", based on plate theory, has been formulated to predict the critical transverse direction (TD) stress at which the web spontaneously lifts off the grit, forming the wrinkle. The model iterates to find the tent shape for a given TD stress, and then uses an interval halving method to determine the critical TD stress. Results from the model will be presented. It turns out that a simpler, analytical "draped beam" model gives similar dependence on parameters but over-predicts the value.Once a wrinkle initiates, it may grow to a size where it is more visible, but has limited length and is restrained against further growth. Further increase in compression enables it to grow by relieving the TD compressive stress in both the lifted-off region and the neighboring web still in contact with the drum. It will also extend in the machine direction (MD). In vacuum coating, wrinkling causes a loss in thermal contact with the cooled drum, the web heats up, expands and the wrinkle grows catastrophically

    Collage Vol. II

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    JUDY COCHRAN: Editorial, 4-5 ROBERTA CHAPMEN: Photo, 6 ANITRA CHUGHTAI (Translations): Haikus, 7 CHARLES O\u27KEEFE: Photo, 8 MARK VANDERLINDE-ABERNATHY, ALYSSA LANDRY (Translator): Memories of a Spider (Les souvenirs d\u27une araignee), 9 MARK VANDERLINE-ABERNATHY, AMY NORSKOG (Translator): Tomato Fields (Champ de tomates), 10 SARAH BISHOP, HEFEDH ZANINA (Translator): Dear John (Cher John), 11 RYAN BUTZ (Translator): Basho\u27s Haiku, Issa\u27s Haiku, 12-13 JENNIFER HUMBERT, FADOUA EL BOUAMRAOUI (Translator): Pressed Lips (Levres Serrees), 15 ADELE REEVES (Translator): Contemporary song by Mr. Children, 16-17 BRODY PAGEL, GRACE DUGAR (Translator): The Lizard King (Le Roi Lezard), 18 JIMMY PIPKIN (Translator): In Love with You, 19 MOLLY ROSCOE: Saturday Night at Rusty\u27s (Samedi Soir a Rusty\u27s), 20 CHARLES O\u27KEEFE: Photo, 21 MATT MESSMER (Translator): Waseda University School Song, 22-23 TIMOTHY COOPER: Wenn du grosh bist… (When you\u27re Tall…), 24 DAVID HARMAN: Der Dunkle Stern (The Dark Star), 25 ANN TOWNSEND, JUDY COCHRAN (Translator): From a Window (D\u27une Fenetre), 26-27 SARA CAHILL: El sauce lloron (The Weeping Willow), 28-32 CHARLES O\u27KEEFE: Photo, 30 JENNIFER HUMBERT, MATT BISHOP: Past, Present (passe, present), 33 CAROL GENEYA KAPLAN, FADOUA EL BOUAMRAOUI (Translator): Une Autre Femme (Another Woman), 34-35 CHARLES O\u27KEEFE: Photo, 36 ANN TOWNSEND, JUDY COCHRAN (Translator): The Mowers (Les Faucheurs), 37 PRISCILLA PATON: Photo, 38 GONZALO TUESTA: La Grande Dame De Paris (The Great Lady of Paris), 39 SARAH PILLERDORF (Translator): Japanese Cartoons by Tezuka Osamu, 41-45 DANIELLE GERKEN: Schuhe der Heimat (Boots of Home), 47 CURTIS PLOWGIAN: Le peste de la langue francaise, 48-52 PRISCILLA PATON: Photo, 50 ZANE HOUSEHOLDER: Vive la Republique! (Film), 54 JENNIFER ZIMMER: EL tenis y las frustraciones (Tennis and Frustrations), La tumba de Ben (Ben\u27s Grave), 56-57 AUTUMN LOTZE: Times Square in the rain, 58-59 CHARLES O\u27KEEFE: Photo, 60 STEPHEN M. JULKA: Colors of the Earth, 61 THOMAS BRESSOUD: Java, 62 ERIC NELSON: World, 63 SARAH CLAPP (Translator): At a long day\u27s end (Natsume Soseki), A friend has come and is now leaving, Eating persimmons (Masaoka Shiki), 64 CHARLES O\u27KEEFE: Photo, 65 JOHN BURZYNSKI, MEGAN FETTER (Translator): Home is where the heart is, 66 RICHARD BANAHAN: Photo, 67 KIM FREEMAN: Baltimore, 68 JACOB RIDRIGUEZ-NOBLE: Home (Heimat), 69 SUZANNE KENNEDY: Oft verberge ich mich (Oft I hide myself), 70 RICHARD BANAHAN: Photo, 7

    Genomic Signatures of Strain Selection and Enhancement in Bacillus atrophaeus var. globigii, a Historical Biowarfare Simulant

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    (BG) as a simulant for biological warfare (BW) agents, knowledge of its genome composition is limited. Furthermore, the ability to differentiate signatures of deliberate adaptation and selection from natural variation is lacking for most bacterial agents. We characterized a lineage of BGwith a long history of use as a simulant for BW operations, focusing on classical bacteriological markers, metabolic profiling and whole-genome shotgun sequencing (WGS). on the nucleotide level. WGS of variants revealed that several strains were mixed but highly related populations and uncovered a progressive accumulation of mutations among the “military” isolates. Metabolic profiling and microscopic examination of bacterial cultures revealed enhanced growth of “military” isolates on lactate-containing media, and showed that the “military” strains exhibited a hypersporulating phenotype.Our analysis revealed the genomic and phenotypic signatures of strain adaptation and deliberate selection for traits that were desirable in a simulant organism. Together, these results demonstrate the power of whole-genome and modern systems-level approaches to characterize microbial lineages to develop and validate forensic markers for strain discrimination and reveal signatures of deliberate adaptation

    Taxation and market power

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    "We analyze the incidence and welfare effects of unit sales taxes in experimental monopoly and Bertrand markets. We find, in line with economic theory, that firms with no market power are able to shift a high share of a tax burden on to consumers, independent of whether buyers are automated or human players. In monopoly markets, a monopolist bears a large share of the burden of a tax increase. With human buyers, however, this share is smaller than with automated buyers as the presence of human buyers constrains the pricing behavior of a monopolist." (author's abstract)"Dieser Artikel untersucht Inzidenz- und Wohlfahrtseffekte einer Mengensteuer in experimentellen Monopol- und Bertrand-Märkten. Im Einklang mit der ökonomischen Theorie sind Firmen ohne Marktmacht in der Lage, einen großen Anteil der Last einer Steuererhöhung an die Konsumenten weiterzugeben. Dies gilt unabhängig davon, ob die Käufer simuliert sind oder die Kaufentscheidungen durch reale Käufer getroffen werden. In Monopolmärkten trägt der Monopolist einen großen Anteil der Last einer Steuererhöhung. Werden die Kaufentscheidungen durch reale Käufer getroffen, ist dieser Anteil jedoch kleiner als mit simulierten Käufern, da reale Käufer im Experiment das Preissetzungsverhalten des Monopolisten einschränken." (Autorenreferat

    Human Embryonic Stem Cells Differentiated to Lung Lineage-Specific Cells Ameliorate Pulmonary Fibrosis in a Xenograft Transplant Mouse Model

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    Our aim was to differentiate human (h) embryonic stem (ES) cells into lung epithelial lineage-specific cells [i.e., alveolar epithelial type I (AEI) and type II (AEII) cells and Clara cells] as the first step in the development of cell-based strategies to repair lung injury in the bleomycin mouse model of idiopathic pulmonary fibrosis (IPF). A heterogeneous population of non-ciliated lung lineage-specific cells was derived by a novel method of embryoid body (EB) differentiation. This differentiated human cell population was used to modulate the profibrotic phenotype in transplanted animals.Omission or inclusion of one or more components in the differentiation medium skewed differentiation of H7 hES cells into varying proportions of AEI, AEII, and Clara cells. ICG-001, a small molecule inhibitor of Wnt/β-catenin/Creb-binding protein (CBP) transcription, changed marker expression of the differentiated ES cells from an AEII-like phenotype to a predominantly AEI-like phenotype. The differentiated cells were used in xenograft transplantation studies in bleomycin-treated Rag2γC(-/-) mice. Human cells were detected in lungs of the transplanted groups receiving differentiated ES cells treated with or without ICG-001. The increased lung collagen content found in bleomycin-treated mice receiving saline was significantly reduced by transplantation with the lung-lineage specific epithelial cells differentiated from ES cells. A significant increase in progenitor number was observed in the airways of bleomycin-treated mice after transplantation of differentiated hES cells.This study indicates that ES cell-based therapy may be a powerful novel approach to ameliorate lung fibrosis
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