Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
175
result(s) for
"Stephenson, Jonathan"
Sort by:
Prospective, Multicenter, Controlled Trial of Mobile Stroke Units
Mobile stroke units have CT scanners and personnel trained to administer tissue plasminogen activator. In a multicity trial, functional outcomes at 90 days after acute stroke were better with mobile stroke units than with standard care by emergency medical services and transfer to an emergency department.
Journal Article
AVOIDING EFFECTIVE PACKING DIMENSION 1 BELOW ARRAY NONCOMPUTABLE C.E. DEGREES
Recent work of Conidis [3] shows that there is a Turing degree with nonzero effective packing dimension, but which does not contain any set of effective packing dimension 1.
This article shows the existence of such a degree below every c.e. array noncomputable degree, and hence that they occur below precisely those of the c.e. degrees which are array noncomputable.
Journal Article
Combination of traumatic thoracic aortic pseudoaneurysm and myocardial contusion leading to left ventricular aneurysm
The combination of thoracic aortic pseudoaneurysm and left ventricular aneurysm resulting from a single traumatic incident is an exceedingly rare occurrence. We present a case of a 10-year-old girl who sustained significant blunt trauma to the chest after being involved in a rollover motor vehicle accident. The child underwent immediate repair of a transected aortic arch. An inferior wall left ventricular aneurysm developed 3 weeks later, and the patient underwent successful repair of the left ventricular aneurysm and a damaged mitral valve. The use of fast multidetector row CT, cardiac MRI, and echocardiography have improved our ability to diagnose these types of injuries and accurately image their anatomic relationships in the acute and perioperative settings.
Journal Article
Interaction and Coevolution of Plants and Arthropods during the Palaeozoic and Mesozoic
Fossil evidence of terrestrial vascular plant life and terrestrial arthropods exists from the Silurian. Fossil evidence suggests progressive interaction between the two groups through the later Palaeozoic and Mesozoic. In this paper we present data, particularly from plant fossils, concerning several interactions: feeding, shelter, transport and reproduction. Evidence of arthropod feeding includes eaten leaves, borings in plant tissues, wound reaction and leaf mining as well as gut contents and coprolites from the arthropods themselves. We trace the changes in leaf eating behaviour from continuous marginal feeding, common in the Palaeozoic and early Mesozoic to the more abundant interrupted-marginal and non- marginal feeding behaviour on Cretaceous angiosperm leaves. This change may reflect the evolution of chemical defence strategies by the plants but may also reflect the evolution of different mouthpart design in new insect groups. Leaf mines and leaf galls, although known from the Upper Carboniferous, only become common in the Cretaceous, coinciding with the evolution of several new insect groups and plants. Wood boring is recorded, for the first time, from the Lower Carboniferous and becomes common from the Upper Carboniferous. Data from coprolites suggest that spore feeding preceded leaf feeding. Experiments using pteridophytes and living arthropods indicate that some spores remain viable after passing through the gut and hence this feeding habit may have also been advantageous to some early plants for propagule transport. We conclude that there is much evidence in the fossil record suggesting plant-arthropod interaction, but many more observations are required before detailed interpretations concerning coevolution can be made.
Journal Article
Topics in computability theory: Boolean algebras and effective packing dimension
This thesis considers problems from two areas of computability theory, and, as such, is divided into two parts. The first part is be the construction of a real number A ≤T 0' which has positive effective packing dimension, but which cannot compute any real number with effective packing dimension 1. The effective packing dimension of a real number is a measure of its complexity, and is a value in [0, 1]. If the effective packing dimension of a real number A lies in (0, 1), we may regard A as being \"partially random\". The real number which is constructed in this section shows a limitation on how much randomness can be computably extracted from a partially random source. This is an extension of a result of Conidis, who carried out a similar construction. However, Conidis' construction was not carried out below 0'. The second part is part of an ongoing program to answer the low n problem for Boolean algebras. The lown problem asks whether every lown Boolean algebra is isomorphic to a computable Boolean algebra. The behaviour for n ≤ 4 suggests that not only do such isomorphisms always exist, but that in each case, 0(n+2) can compute one such isomorphism. Harris and Montalbán constructed a low5 Boolean algebra which refutes the purported bound. This part of the thesis develops machinery which proves that any counterexample along the lines of that given by Harris and Montalbán must occur as a member of an infinite family. In particular, using the method of Harris and Montalbán, the machinery shows that for each n there is a low2n+5 Boolean algebra which is not isomorphic to any low2n+4 Boolean algebra via any 0(2n+7)-computable map.
Dissertation
Fossil evidence for plant-arthropod interactions in the Palaeozoic and Mesozoic,Fossil evidence for plant-animal interactions in the Palaeozoic and Mesozoic
Some of the earliest Devonian fossils of vascular plants show lesions that may be attributed to plant feeding activity by animals. This is the beginning of a more or less continuous fossil record of plant-animal interactions which extends from the Devonian to the present day. An important feature of pre-Cretaceous material is the evidence from coprolites and gut-contents of spore eating by arthropods. Experiments with living arthropods, of groups represented in the Palaeozoic, show that viable spores can survive passage through the gut in significant numbers. Spore eating could clearly have had a dispersal role of value to the plant, as well as its evident benefit as a source of nutrition for the animal involved. Evidence of wood boring and leaf eating extends from the late Carboniferous onwards. It appears that ‘continuous marginal’ leaf-feeding preceded 'interrupted marginal’ feeding, and that this was in turn followed by ‘non-marginal’ leaf feeding. The latter first appeared in Cretaceous angiosperms. Some diversity of leaf miners and leaf galls are also represented in Cretaceous angiosperm leaf fossils.
Journal Article