5,928 research outputs found

    Anisotropy of the Microwave Sky at 90 GHz: Results from Python II

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    We report on additional observations of degree scale anisotropy at 90~GHz from the Amundsen-Scott South Pole Station in Antarctica. Observations during the first season with the Python instrument yielded a statistically significant sky signal; in this paper we report the confirmation of that signal with data taken in the second year, and on results from an interleaving set of fields.Comment: 10 pages, plus 2 figures. Postscript and uufiles versions available via anonymous ftp at ftp://astro.uchicago.edu/pub/astro/ruhl/pyI

    Opposing shear senses in a subdetachment mylonite zone: Implications for core complex mechanics

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    [1] Global studies of metamorphic core complexes and low‐angle detachment faults have highlighted a fundamental problem: Since detachments excise crustal section, the relationship between the mylonitic rocks in their footwalls and the brittle deformation in their hanging walls is commonly unclear. Mylonites could either reflect ductile deformation related to exhumation along the detachment fault, or they could be a more general feature of the extending middle crust that has been “captured ” by the detachment. In the first case we would expect the kinematics of the mylonite zone to mirror the sense of movement on the detachment; in the second case both the direction and sense of shear in the mylonites could be different. The northern Snake Range dĂ©collement (NSRD) is a classic Basin and Range detachment fault with a well‐documented top‐east of displacement. We present structural, paleo-magnetic, geochronological, and geothermometric evidence to suggest that the mylonite zone below the NSRD locally experienced phases of both east ‐ and west‐directed shear, inconsistent with movement along a single detachment fault. We therefore propose that the footwall mylonites represent a predetachment dis-continuity in the middle crust that separated localized deformation above from distributed crustal flow below (localized‐distributed transition (LDT)). The mylonites were subsequently captured by a moderately dipping brittle detachment that soled down to the middle crust and exhumed them around a rolling hinge into a subhorizontal orientation at the surface, produc-ing the present‐day NSRD. In this interpretation the brittle hanging wall represents a series of rotated upper crustal normal faults, whereas the mylonitic footwall represents one or more exhumed middl

    Effect of breastfeeding on gastrointestinal infection in infants: A targeted maximum likelihood approach for clustered longitudinal data

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    The PROmotion of Breastfeeding Intervention Trial (PROBIT) cluster-randomized a program encouraging breastfeeding to new mothers in hospital centers. The original studies indicated that this intervention successfully increased duration of breastfeeding and lowered rates of gastrointestinal tract infections in newborns. Additional scientific and popular interest lies in determining the causal effect of longer breastfeeding on gastrointestinal infection. In this study, we estimate the expected infection count under various lengths of breastfeeding in order to estimate the effect of breastfeeding duration on infection. Due to the presence of baseline and time-dependent confounding, specialized "causal" estimation methods are required. We demonstrate the double-robust method of Targeted Maximum Likelihood Estimation (TMLE) in the context of this application and review some related methods and the adjustments required to account for clustering. We compare TMLE (implemented both parametrically and using a data-adaptive algorithm) to other causal methods for this example. In addition, we conduct a simulation study to determine (1) the effectiveness of controlling for clustering indicators when cluster-specific confounders are unmeasured and (2) the importance of using data-adaptive TMLE.Comment: Published in at http://dx.doi.org/10.1214/14-AOAS727 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    A comparison of the distribution of pneumococcal types in systemic disease and the upper respiratory tract in adults and children

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    The serotype distribution of 874 strains of Streptococcus pneumoniae was determined in relation to patients' age and to frequency of isolation from systemic disease. Types 14 and 18, in pre-school children, and types 1, 4, 7, 8 and 12 in patients over 5 years of age were significantly associated with systemic disease whereas type 23 in pre-school children, and type 6 in older patients was associated with upper respiratory tract carriage. No significant difference was found in the incidence of other types in systemic disease compared to upper respiratory tract carriage. Fifteen diagnostic pneumococcal antisera (to types 1, 3, 4, 6, 7, 8, 9, 11, 12, 14, 17, 18, 19, 22 and 23) sufficed for typing 87% of strains

    Response of a native bamboo [Arundinaria gigantea (Walt.) Muhl.] in a wind-disturbed forest

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    Numerous bamboos are known to form extensive single-species stands, including species in the United States. Formerly prominent in the southeastern US, canebrakes are dense stands of the bamboos collectively called cane [Arundinaria (Michx)]. Canebrakes are now a critically endangered component of the bottomland hardwood forest ecosystem. Cane still occurs in its historic range, primarily in small remnant patches. A poor understanding of the ecological processes that generated large canebrakes limits their restoration and management. We hypothesize that cane\u27s spreading clonal structure enables these bamboos to persist beneath a forest canopy and then respond rapidly to large-scale wind disturbances. We quantified patterns of clonal growth in one cane species, giant cane [Arundinaria gigantea (Walt.) Muhl.], in a very large tornado-generated canopy gap and in surrounding bottomland hardwood forest in Louisiana. We tested these four hypotheses over a 12-month study period in the large canopy gap: (1) production of new culms should be greater, (2) clonal expansion should be greater, (3) culm damage rate should be reduced, and (4) culm size should be reduced compared to giant cane stands under forest canopy. We found that new culm production in tornado-blowdown plots was twice that in forest plots. Accordingly, culms were younger on average in the tornado blowdown than under forest. Rate of clonal expansion was similar between the two environments, suggesting clonal spread was not disturbance-dependent. With fewer branch-fall impacts, culms in the tornado blowdown were less often damaged. Culms were smaller in tornado-blowdown plots than in forest plots. Giant cane\u27s clonal plasticity should enable it to persist in old-growth bottomland forests by responding to local light conditions. Genets should increase culm production in small gaps and senesce as gaps fill in. Giant cane stands could thereby shift location over time. Wind disturbance that opens forest canopy should trigger redevelopment of denser stands that could merge with other expanding stands into expansive canebrakes. Giant cane\u27s clonal ecology may be a useful model for understanding spreading bamboos and other forest-growing clonal perennials. © 2007 Elsevier B.V. All rights reserved

    Applying Workspace Limitations in a Velocity-Controlled Robotic Mechanism

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    A robotic system includes a robotic mechanism responsive to velocity control signals, and a permissible workspace defined by a convex-polygon boundary. A host machine determines a position of a reference point on the mechanism with respect to the boundary, and includes an algorithm for enforcing the boundary by automatically shaping the velocity control signals as a function of the position, thereby providing smooth and unperturbed operation of the mechanism along the edges and corners of the boundary. The algorithm is suited for application with higher speeds and/or external forces. A host machine includes an algorithm for enforcing the boundary by shaping the velocity control signals as a function of the reference point position, and a hardware module for executing the algorithm. A method for enforcing the convex-polygon boundary is also provided that shapes a velocity control signal via a host machine as a function of the reference point position

    Toward a solution for cardiac failure in the newborn

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    The newborn infant with severe cardiac failure owed to congenital structural heart disease or cardiomyopathy poses a daunting therapeutic challenge. The ideal solution for both might be cardiac transplantation if availability of hearts was not limiting and if tolerance could be induced, obviating toxicity of immunosuppressive therapy. If one could safely and effectively exploit neonatal tolerance for successful xenotransplantation of the heart, the challenge of severe cardiac failure in the newborn infant might be met. We discuss the need, the potential for applying neonatal tolerance in the setting of xenotransplantation and the possibility that other approaches to this problem might emerge.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146972/1/xen12479.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146972/2/xen12479_am.pd
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