1,943 research outputs found
Revision of a late Middle Cambrian trilobite faunule from Northwestern Queensland
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
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
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
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
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
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
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
Caryospora duszynskii (Apicomplexa: Eimeriidae) from the Speckled Kingsnake, Lampropeltis holbrooki (Reptilia: Ophidia), in Arkansas, with a Summary of PreviousReports
- …