oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 8 )

2019 ( 263 )

2018 ( 428 )

2017 ( 433 )

Custom range...

Search Results: 1 - 10 of 232158 matches for " Robert L. Dunstone "
All listed articles are free for downloading (OA Articles)
Page 1 /232158
Display every page Item
A Gigantic Sarcopterygian (Tetrapodomorph Lobe-Finned Fish) from the Upper Devonian of Gondwana (Eden, New South Wales, Australia)
Ben Young, Robert L. Dunstone, Timothy J. Senden, Gavin C. Young
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0053871
Abstract: Edenopteron keithcrooki gen. et sp. nov. is described from the Famennian Worange Point Formation; the holotype is amongst the largest tristichopterids and sarcopterygians documented by semi-articulated remains from the Devonian Period. The new taxon has dentary fangs and premaxillary tusks, features assumed to be derived for large Northern Hemisphere tristichopterids (Eusthenodon, Hyneria, Langlieria). It resembles Eusthenodon in ornament, but is distinguished by longer proportions of the parietal compared to the post-parietal shield, and numerous differences in shape and proportions of other bones. Several characters (accessory vomers in the palate, submandibulars overlapping ventral jaw margin, scales ornamented with widely-spaced deep grooves) are recorded only in tristichopterids from East Gondwana (Australia-Antarctica). On this evidence Edenopteron gen. nov. is placed in an endemic Gondwanan subfamily Mandageriinae within the Tristichopteridae; it differs from the nominal genotype Mandageria in its larger size, less pointed skull, shape of the orbits and other skull characters. The hypothesis that tristichopterids evolved in Laurussia and later dispersed into Gondwana, and a derived subgroup of large Late Devonian genera dispersed from Gondwana, is inconsistent with the evidence of the new taxon. Using oldest fossil and most primitive clade criteria the most recent phylogeny resolves South China and Gondwana as areas of origin for all tetrapodomorphs. The immediate outgroup to tristichopterids remains unresolved – either Spodichthys from Greenland as recently proposed, or Marsdenichthys from Gondwana, earlier suggested to be the sister group to all tristichopterids. Both taxa combine two characters that do not co-occur in other tetrapodomorphs (extratemporal bone in the skull; non-cosmoid round scales with an internal boss). Recently both ‘primitive’ and ‘derived’ tristichopterids have been discovered in the late Middle Devonian of both hemispheres, implying extensive ghost lineages within the group. Resolving their phylogeny and biogeography will depend on a comprehensive new phylogenetic analysis.
Status and Distribution of Otters In the Amboro National Park, Bolivia
Dunstone N.,Strachan R.
IUCN Otter Specialist Group Bulletin , 1988,
Abstract: Otters have not fared well in the presence of man, both species have been extensively hunted for their pelts. In recent years an even greater threat is posed by the dynamiting and poisoning of rivers and clearance of bankside vegetation. Amboro is a relatively new National Park and should be regarded as a showpiece for Bolivia. The foresight of the Government, C.D.F., Prodena Bolivia, and particularly Reginald Hardy and Robin Clarke in getting this venture off the ground and for their continuing support is commendable. Considerable problems remain however, paramount of which, is the hunting of animals for food, for live export or for skins. Ample evidence of this practise has been found on both visits to Amboro. Pteronura brasiliensis occurred commonly in the Park up until 10 years ago, and was hunted for its pelt until 15 years ago. The species of otter which was commonly encountered was the neotropical river otter (Lutra longicaudis). As far as the otter populations are concerned, direct persecution is now minimal since there is no market for their skins. However the practise of fishing using dynamite or poison should be actively discouraged if the good populations of these animals are to be maintained.
Heinrich’s Fourth Dimension  [PDF]
Robert L. Collins
Open Journal of Safety Science and Technology (OJSST) , 2011, DOI: 10.4236/ojsst.2011.11003
Abstract: In this article, the author uses accident data readily available from the United States Bureau of Labor Statistics to create a New Incident Pyramid, a modern day equivalent of Heinrich’s Triangle. This historical data is then combined with generally accepted statistical methods to show that the relationship between incident types first envisioned by Herbert William Heinrich in 1931 has a fourth dimension, time. Using statistical analysis methods derived from both a Binomial distribution and a Poisson distribution, this analysis will show how information derived from these accident summaries can be used to predict potential future events. The obvious conclusion reinforced by this analysis will be that the future date for potentially fatal accidents can only be delayed by focusing on accident prevention strategies that address all incidents without regard for the type of resulting injury. This analysis can be used by safety professionals to predict potential future outcomes for their establishments which can then be used to better communicate the need for improvements in accident prevention programs.
Discrete Scale Relativity and SX Phoenicis Variable Stars  [PDF]
Robert L Oldershaw
International Journal of Astronomy and Astrophysics (IJAA) , 2011, DOI: 10.4236/ijaa.2011.12006
Abstract: Discrete Scale Relativity proposes a new symmetry principle called discrete cosmological self-similarity which relates each class of systems and phenomena on a given Scale of nature’s discrete cosmological hierarchy to the equivalent class of analogue systems and phenomena on any other Scale. The new symmetry principle can be understood in terms of discrete scale invariance involving the spatial, temporal and dynamic parameters of all systems and phenomena. This new paradigm predicts a rigorous discrete self-similarity between Stellar Scale variable stars and Atomic Scale excited atoms undergoing energy-level transitions and sub-threshold oscillations. Previously, methods for demonstrating and testing the proposed symmetry principle have been applied to RR Lyrae, δ Scuti and ZZ Ceti variable stars. In the present paper we apply the same analytical methods and diagnostic tests to a new class of variable stars: SX Phoenicis variables. Double-mode pulsators are shown to provide an especially useful means of testing the uniqueness and rigor of the conceptual principles and discrete self-similar scaling of Discrete Scale Relativity. These research efforts will help theoretical physicists to understand the fundamental discrete self-similarity of nature, and to model both stellar and atomic systems with one unified physics.
On Dynamics in a Quasi-Measurement Field  [PDF]
Robert L. Shuler
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.41018
Abstract:

A general theory of inertia tends to be circular because momentum and therefore inertia are taken as assumptions in quantum field theories. In this paper we explore instead using position uncertainty to infer inertia with mediation by quasi-measurement interactions. This method avoids attachment to the reference frame of the source masses and is thus completely relativistic, overcoming a conflict between historical theories of inertia and relativity. We investigate what laws of motion result, and whether natural explanations for equivalence and dark energy emerge.

Integration of the Classical Action for the Quartic Oscillator in 1 + 1 Dimensions  [PDF]
Robert L. Anderson
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.410A3014
Abstract:

In this paper, we derive an explicit form in terms of end-point data in space-time for the classical action, i.e. integration of the Lagrangian along an extremal, for the nonlinear quartic oscillator evaluated on extremals.

Dynamic Transverse Deflection of a Free Mild-Steel Plate  [PDF]
Robert L. Bish
World Journal of Mechanics (WJM) , 2013, DOI: 10.4236/wjm.2013.39037
Abstract:

The problem analytically investigated is that a thin free plate of mild-steel struck at normal incidence by a flat ended rigid rod moving at high velocity. As in quasi-static deformation by extended slip, the strain-rate tensor is solenoidal and under dynamic loading conditions the Tresca yield criterion is modified so that the solenoidal property replaces the hypothesis of a viscoplastic overstress. Overstress then arises from inertial body forces and the high magnitudes found, in the following, for these forces are due to the influence of the propagating boundary. Two new theorems are proven. These theorems show that the deflection in the plate is entirely transverse, even in the case of indefinitely large punch deflections, and that the lines of equal transverse deflection in the plate are also principal lines of stress and strain-rate, as are the lines of steepest descent. A formula is obtained giving the inertial force opposing the punch as a function of the time and the theoretical deflection profile on a plate deformed by a flat-ended punch of circular section is presented. The stresses in the plate are then analyzed and it is shown that the stress inside the boundary in the direction of propagation, equals ρc2where ρ is the mass density of the plate material and the boundary wave propagates at speed c which, it is shown, is equal to one-half of the velocity of elastic waves of rotation in the solid concerned.

The Twins Clock Paradox History and Perspectives  [PDF]
Robert L. Shuler Jr.
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.512108
Abstract:

The twins or clock paradox has been a subject of lively discussion and occasional disagreement among both relativists and the public for over 100 years, and continues to attract physicists who write papers giving new analyses or defending old ones, even though many physicists now consider the matter only of educational interest. This paper investigates the number of papers, which is increasing, and trends in explanations, some of which are now targeted at professional physicists and other of which are targeted at optical or radar visualization rather than problem solving. Observations of students indicate that the latest techniques help but only somewhat. An analysis is made of 21 previous treatments appearing in the education related American Journal of Physics, Einstein’s discussions and several other pedagogical papers. A new memory aid for simultaneity transformation is given that puts it on a par with “time dilation” and “length contraction” for quick and easy problem visualization. The point of view of a trailing twin is introduced to show how simultaneity changes account for missing time in the turnaround. Length contraction is treated on equal footing with time dilation, and Swann’s insight into clocks is extended to lengths. Treatments using the conventionality of simultaneity are seen as equivalent to choice of co-moving frames. Responses to difficult questions are suggested which avoid being dismissive, and engage students’ critical thinking.

Green’s Function for the Quartic Oscillator  [PDF]
Robert L. Anderson
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.714135
Abstract: In this paper, a quantum mechanical Green’s function \"\"?for the quartic oscillator is presented. This result is built upon two previous papers: first [1], detailing the linearization of the quartic oscillator (qo) to the harmonic oscillator (ho); second [2], the integration of the classical action function for the quartic oscillator. Here an equivalent form for the quartic oscillator action function \"\"?in terms of harmonic oscillator variables is derived in order to facilitate the derivation of the quartic oscillator Green’s Function, namely in fixing its amplitude.
Spatially-Explicit, Exposure-Based Assessment of Surface Water Vulnerability from Land Use Threats for Time-Efficient and Cost-Effective Watershed Development Planning  [PDF]
Robert L. France, Gary Pardy
Journal of Geoscience and Environment Protection (GEP) , 2018, DOI: 10.4236/gep.2018.66003
Abstract: The utility of a spatially-explicit, exposure-based model was examined for its suitability as a tool for rapidly assessing surface water vulnerability in watershed planning. This simple GIS-model uses three types of easily obtainable spatial information: (1) sources of land use-induced change; (2) intensity of watershed drainage; and (3) sensitivity of drainage basins to change. This model was applied to the Thomas Brook watershed in Nova Scotia, Canada, which has been the site of previous studies, conducted over multiple years, using detailed, effects-based, hydrologic models. Doing so allowed us the opportunity to compare the two approaches. Results showed a good concordance in the derived mapped outputs between the two models. Given the rapid ease and inexpensive cost of using the GIS, exposure-based model, we believe it to offer great promise in terms of prioritizing locations for further study or for intervention of best management practices, as well as for planning where to best direct future water-sensitive development through build-out analyses.
Page 1 /232158
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.