1,721,404 research outputs found
AGD control and disinfection in cleanerfish: Part 2: Challenge trial
Full text linkJuvenile ballan wrasse, Labrus bergylta were exposed to a Neoparamoeba perurans polyculture either UV irradiated at a low (2mJ cm-2) or high (20mJ cm-2) dose of UV radiation from a medium pressure UV lamp in a beam collimeter. Control fish consisted of un-exposed fish and fish exposed to non-irradiated Neoparamoeba perurans. Over the subsequent 6 weeks of maintainenance, amoebic gill disease (AGD) only developed in the nonirradiated amoeba challenged group with a gross gill score peaking at 3 with 100% prevalence. Similarly, only the non-irradiated amoeba group showed characteristic AGD pathology and was the only group in which Neoparamoeba peruans were detected by PCR. This study indicated that UV irradiation of Neoparamoeba peruans is sufficient to prevent the onset of infection if irradiation exceeds 2 mJ cm-2Marine Harvest ASApublishedVersio
Counterexamples in 4-manifold topology
Full text linkWe illustrate the rich landscape of 4-manifold topology through the lens of
counterexamples. We consider several of the most commonly studied equivalence
relations on 4-manifolds and how they are related to one another. We explain
implications e.g. that -cobordant manifolds are stably homeomorphic, and we
provide examples illustrating the failure of other potential implications. The
information is conveniently organised in a flowchart and a table.Comment: 37 pages, 4 figures, 1 table; in v2, we have made several changes in
response to a referee report, including writing a more detailed introduction,
adding more details about the surgery exact sequence, uniformising the
structure of the subsections describing counterexamples, and adding
Proposition 5.6. This is the version published in EMS Survey
Homotopy classification of 4-manifolds with finite abelian 2-generator fundamental groups
Full text linkWe show that for an oriented 4-dimensional Poincaré complex with finite fundamental group, whose 2-Sylow subgroup is abelian with at most 2 generators, the homotopy type is determined by its quadratic 2-type.17 pages. Minor changes following a referee report. To appear in Mathematical Proceedings of the Cambridge Philosophical Societ
Shrinking of toroidal decomposition spaces
Full text linkGiven a sequence of oriented links L1,L2,L3,… each of which has a distinguished, unknotted component, there is a decomposition space D of S3 naturally associated to it, which is constructed as the components of the intersection of an infinite sequence of nested solid tori. The Bing and Whitehead continua are simple, well known examples. We give a necessary and sufficient criterion to determine whether D is shrinkable, generalising previous work of F. Ancel and M. Starbird and others. This criterion can effectively determine, in many cases, whether the quotient map S3→S3/D can be approximated by homeomorphisms
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Embedding surfaces in 4-manifolds
Full text linkWe prove a surface embedding theorem for 4-manifolds with good fundamental group in the presence of dual spheres, with no restriction on the normal bundles. The new obstruction is a Kervaire-Milnor invariant for surfaces and we give a combinatorial formula for its computation. For this we introduce the notion of band characteristic surfaces.56 pages, 20 figures; in v2, we have added a new section (Section 1.5) containing applications to knot theory; v3: several minor changes and corrections following a referee report, to appear in Geometry & Topolog
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