26,513 research outputs found
Simulations of the Population of Centaurs II: Individual Objects
Detailed orbit integrations of clones of five Centaurs -- namely, 1996 AR20,
2060 Chiron, 1995 SN55, 2000 FZ53 and 2002 FY36 -- for durations of 3 Myr are
presented. One of our Centaur sample starts with perihelion initially under the
control of Jupiter (1996 AR20), two start under the control of Saturn (Chiron
and 1995 SN55) and one each starts under the control of Uranus (2000 FZ53) and
Neptune (2002 FY36) respectively. A variety of interesting pathways are
illustrated with detailed examples including: capture into the Jovian Trojans,
repeated bursts of short-period comet behaviour, capture into mean-motion
resonances with the giant planets and into Kozai resonances, as well as
traversals of the entire Solar system. For each of the Centaurs, we provide
statistics on the numbers (i) ejected, (ii) showing short-period comet
behaviour and (iii) becoming Earth and Mars crossing. For example, Chiron has
over 60 % of its clones becoming short-period objects, whilst 1995 SN55 has
over 35 %. Clones of these two Centaurs typically make numerous close
approaches to Jupiter. At the other extreme, 2000 FZ53 has roughly 2 % of its
clones becoming short-period objects. In our simulations, typically 20 % of the
clones which become short-period comets subsequently evolve into
Earth-crossers.Comment: 10 pages, in press at MNRA
Large boron--epoxy filament-wound pressure vessels
Advanced composite material used to fabricate pressure vessel is prepeg (partially cured) consisting of continuous, parallel boron filaments in epoxy resin matrix arranged to form tape. To fabricate chamber, tape is wound on form which must be removable after composite has been cured. Configuration of boron--epoxy composite pressure vessel was determined by computer program
Defining and Meeting the Demand for Agricultural Machinery in China: A Case Study of John Deere
China, Machinery markets, John Deere, Agribusiness, Demand and Price Analysis, Marketing, Public Economics,
Analysis and application of digital spectral warping in analog and mixed-signal testing
Spectral warping is a digital signal processing transform which shifts the frequencies contained within a signal along the frequency axis. The Fourier transform coefficients of a warped signal correspond to frequency-domain 'samples' of the original signal which are unevenly spaced along the frequency axis. This property allows the technique to be efficiently used for DSP-based analog and mixed-signal testing. The analysis and application of spectral warping for test signal generation, response analysis, filter design, frequency response evaluation, etc. are discussed in this paper along with examples of the software and hardware implementation
Exercise redox biochemistry:conceptual, methodological and technical recommendations
Exercise redox biochemistry is of considerable interest owing to its translational value in health and disease. However, unaddressed conceptual, methodological and technical issues complicate attempts to unravel how exercise alters redox homeostasis in health and disease. Conceptual issues relate to misunderstandings that arise when the chemical heterogeneity of redox biology is disregarded which often complicate attempts to use redox-active compounds and assess redox signalling. Further, that oxidised macromolecule adduct levels reflect formation and repair is seldom considered. Methodological and technical issues relate to the use of out-dated assays and/or inappropriate sample preparation techniques that confound biochemical redox analysis. After considering each of the aforementioned issues, we outline how each issue can be resolved and provide a unifying set of recommendations. We specifically recommend that investigators: consider chemical heterogeneity, use redox-active compounds judiciously, abandon flawed assays, carefully prepare samples and assay buffers, consider repair/metabolism, use multiple biomarkers to assess oxidative damage and redox signalling
The Populations of Comet-Like Bodies in the Solar system
A new classification scheme is introduced for comet-like bodies in the Solar
system. It covers the traditional comets as well as the Centaurs and
Edgeworth-Kuiper belt objects. At low inclinations, close encounters with
planets often result in near-constant perihelion or aphelion distances, or in
perihelion-aphelion interchanges, so the minor bodies can be labelled according
to the planets predominantly controlling them at perihelion and aphelion. For
example, a JN object has a perihelion under the control of Jupiter and aphelion
under the control of Neptune, and so on. This provides 20 dynamically distinct
categories of outer Solar system objects in the Jovian and trans-Jovian
regions. The Tisserand parameter with respect to the planet controlling
perihelion is also often roughly constant under orbital evolution. So, each
category can be further sub-divided according to the Tisserand parameter. The
dynamical evolution of comets, however, is dominated not by the planets nearest
at perihelion or aphelion, but by the more massive Jupiter. The comets are
separated into four categories -- Encke-type, short-period, intermediate and
long-period -- according to aphelion distance. The Tisserand parameter
categories now roughly correspond to the well-known Jupiter-family comets,
transition-types and Halley-types. In this way, the nomenclature for the
Centaurs and Edgeworth-Kuiper belt objects is based on, and consistent with,
that for comets.Comment: MNRAS, in press, 11 pages, 6 figures (1 available as postscript, 5 as
gif). Higher resolution figures available at
http://www-thphys.physics.ox.ac.uk/users/WynEvans/preprints.pd
MEME Suite: tools for motif discovery and searching
The MEME Suite web server provides a unified portal for online discovery and analysis of sequence motifs representing features such as DNA binding sites and protein interaction domains. The popular MEME motif discovery algorithm is now complemented by the GLAM2 algorithm which allows discovery of motifs containing gaps. Three sequence scanning algorithms—MAST, FIMO and GLAM2SCAN—allow scanning numerous DNA and protein sequence databases for motifs discovered by MEME and GLAM2. Transcription factor motifs (including those discovered using MEME) can be compared with motifs in many popular motif databases using the motif database scanning algorithm Tomtom. Transcription factor motifs can be further analyzed for putative function by association with Gene Ontology (GO) terms using the motif-GO term association tool GOMO. MEME output now contains sequence LOGOS for each discovered motif, as well as buttons to allow motifs to be conveniently submitted to the sequence and motif database scanning algorithms (MAST, FIMO and Tomtom), or to GOMO, for further analysis. GLAM2 output similarly contains buttons for further analysis using GLAM2SCAN and for rerunning GLAM2 with different parameters. All of the motif-based tools are now implemented as web services via Opal. Source code, binaries and a web server are freely available for noncommercial use at http://meme.nbcr.net
Putative fishery-induced changes in biomass and population size structures of demersal deep-sea fishes in ICES Sub-area VII, Northeast Atlantic Ocean
This work was supported by a series of NERC grants to the principal investigators including NE/C512961/1. The results of the early joint SAMS and IOS surveys were digitized with support from EU MAST Contract MAS2-CT920033 1993–1995, and data analyses was supported by EU FP7 Projects HERMES and HERMIONE. We thank Alain Zuur from Highland Statistics Ltd. for advice with the statistical analyses and Odd Aksel Bergstad for valuable comments that helped to improve the manuscript. We thank the ships’ companies of the RRS Challenger and RRS Discovery.Peer reviewedPublisher PD
Interplay of individual interactions and turbidity affects the functional response of three-spined sticklebacks \u3ci\u3eGasterosteus aculeatus\u3c/i\u3e
The effects of turbidity, size and the presence of conspecifics on the functional response, feeding latency and activity in the three-spined stickleback Gasterosteus aculeatus were examined. A significant interaction between standard length and presence of conspecifics demonstrated an increase in attack rates of larger individuals in the presence of conspecifics. Attack rate was also higher in turbid water. Feeding latency decreased with prey concentration and presence of conspecifics, but was not affected by turbidity. Activity level did not change with prey levels, but increased with turbidity. These results can help to better understand how individual flexibility in the functional response can affect prey mortality according to environmental perturbation and social interaction at the level of the predator
- …