1,943 research outputs found

    How to plant forest trees (1993)

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    Reviewed October 1993

    Revision of a late Middle Cambrian trilobite faunule from Northwestern Queensland

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    26 p., 4 pl., 2 fig.http://paleo.ku.edu/contributions.htm

    The remarkable squidworm is an example of discoveries that await in deep-pelagic habitats

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    Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of Royal Society for personal use, not for redistribution. The definitive version was published in Biology Letters 7 (2011): 449-453, doi:10.1098/rsbl.2010.0923.An intriguing new annelid, Teuthidodrilus samae (Annelida, Cirratuliformia) gen. and sp. nov., was observed and collected during deep water column exploration of the western Celebes Sea. The Celebes Sea is a deep pocket basin, effectively isolated from surrounding deep water, and is part of the Coral Triangle, a focal area for conservation because of its high diversity and unique geological history. Collected specimens reached 94 mm in length and possessed 10 anterior appendages that were as long or longer than the body. Two characters distinguish T. samae from other polychaetes: notochaetae forming broad, concavo-convex paddles, and six pairs of free-standing, oppositely branched nuchal organs. Phylogenetic analysis of five genes and a 29 character morphological matrix showed that T. samae is an acrocirrid (primarily benthic polychaetes) belonging to the morphologically diverse swimming clade. Pelagic animals within primarily benthic clades are of particular interest in evolutionary biology, because their adaptations to life in the water column inform us of the evolutionary possibilities and constraints within the clade and indirectly of the selective pressures at work in this unfamiliar habitat. This new genus illustrates how much we have to learn about even the large, abundant inhabitants of deep-pelagic communities.Funding was provided to LPM by grants from NOAA’s Office of Ocean Exploration and WHOI Ocean Life Institute, with additional support from the National Geographic Society. The University of California President’s Postdoctoral Fellowship provided funding to KJO

    Synthesis and analysis of jet fuel from shale oil and coal syncrudes

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    Thirty-two jet fuel samples of varying properties were produced from shale oil and coal syncrudes, and analyzed to assess their suitability for use. TOSCO II shale oil and H-COAL and COED syncrudes were used as starting materials. The processes used were among those commonly in use in petroleum processing-distillation, hydrogenation and catalytic hydrocracking. The processing conditions required to meet two levels of specifications regarding aromatic, hydrogen, sulfur and nitrogen contents at two yield levels were determined and found to be more demanding than normally required in petroleum processing. Analysis of the samples produced indicated that if the more stringent specifications of 13.5% hydrogen (min.) and 0.02% nitrogen (max.) were met, products similar in properties to conventional jet fuels were obtained. In general, shale oil was easier to process (catalyst deactivation was seen when processing coal syncrudes), consumed less hydrogen and yielded superior products. Based on these considerations, shale oil appears to be preferred to coal as a petroleum substitute for jet fuel production

    Time evolution and observables in constrained systems

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    The discussion is limited to first-class parametrized systems, where the definition of time evolution and observables is not trivial, and to finite dimensional systems in order that technicalities do not obscure the conceptual framework. The existence of reasonable true, or physical, degrees of freedom is rigorously defined and called {\em local reducibility}. A proof is given that any locally reducible system admits a complete set of perennials. For locally reducible systems, the most general construction of time evolution in the Schroedinger and Heisenberg form that uses only geometry of the phase space is described. The time shifts are not required to be 1symmetries. A relation between perennials and observables of the Schroedinger or Heisenberg type results: such observables can be identified with certain classes of perennials and the structure of the classes depends on the time evolution. The time evolution between two non-global transversal surfaces is studied. The problem is posed and solved within the framework of the ordinary quantum mechanics. The resulting non-unitarity is different from that known in the field theory (Hawking effect): state norms need not be preserved so that the system can be lost during the evolution of this kind.Comment: 31 pages, Latex fil

    Hemoparasites (Apicomplexa: Hepatozoon; Kinetoplastida: Trypanosoma) of Green Frogs, Rana clamitans (Anura: Ranidae) from Arkansas

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    The green frog, Rana clamitans, has been reported as a host of several hemoparasites, including trypanosomes and Hepatozoon spp. In Arkansas, however, there are no reports of any hemoparasites in R. clamitans nor from any other anuran from the state. We collected 9 green frogs from Polk County and blood was taken from their facial musculocutaneous vein in heparinized capillary tubes. Thin blood smears were also made and stained with DipQuick stain. Seven out of 9 (78%) R. clamitans were infected with hematozoans. Three (33%) were infected with an unknown species of Hepatozoon and 4 (44%) were infected with trypanosomes of 3 distinct morphologies. Mixed infections were found in 5 (56%) of the hosts. Here, we provide the first report of hemoparasites in R. clamitans from Arkansas, including morphometric data and photomicrographs of the infections

    Assessing Photoreceptor Structure Associated with Ellipsoid Zone Disruptions Visualized with Optical Coherence Tomography

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    Purpose: To compare images of photoreceptor layer disruptions obtained with optical coherence tomography (OCT) and adaptive optics scanning light ophthalmoscopy (AOSLO) in a variety of pathologic states.Methods: Five subjects with photoreceptor ellipsoid zone disruption as per OCT and clinical diagnoses of closed-globe blunt ocular trauma (n = 2), macular telangiectasia type 2 (n = 1), blue-cone monochromacy (n = 1), or cone-rod dystrophy (n = 1) were included. Images were acquired within and around photoreceptor lesions using spectral domain OCT, confocal AOSLO, and split-detector AOSLO.Results: There were substantial differences in the extent and appearance of the photoreceptor mosaic as revealed by confocal AOSLO, split-detector AOSLO, and spectral domain OCT en face view of the ellipsoid zone.Conclusion: Clinically available spectral domain OCT, viewed en face or as B-scan, may lead to misinterpretation of photoreceptor anatomy in a variety of diseases and injuries. This was demonstrated using split-detector AOSLO to reveal substantial populations of photoreceptors in areas of no, low, or ambiguous ellipsoid zone reflectivity with en face OCT and confocal AOSLO. Although it is unclear if these photoreceptors are functional, their presence offers hope for therapeutic strategies aimed at preserving or restoring photoreceptor function

    Comparison of A-mode and B-mode Ultrasound for Measurement of Subcutaneous Fat

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    With lower-cost devices and technologic advancements, ultrasound has been undergoing a resurgence as a method to measure subcutaneous adipose tissue. We aimed to determine whether a low-cost, 2.5-MHz amplitude (A-mode) ultrasound, designed specifically for body composition assessment, could produce subcutaneous fat thickness measurements comparable to an expensive, 12-MHz brightness (B-mode) device. Fat thickness was measured on 40 participants (20 female, 20 male; 29.7 ± 11.1 y of age; body mass index 24.9 ± 4.5 kg/m2) at 7 sites (chest, subscapula, mid-axilla, triceps, abdomen, suprailiac and thigh) with both devices. Intraclass correlations exceeded 0.75 at all measurement sites. Mean differences in fat thickness were not significantly different (p \u3e 0.05) and within ± 1.0 mm. Variability between devices was greatest at the abdomen, the site with the greatest thickness. The low-cost, low-resolution A-mode ultrasound provides subcutaneous fat thickness measurements similar to the more expensive, high-resolution B-mode ultrasound
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