122,196 research outputs found
Diameter Bounds on the Complex of Minimal Genus Seifert Surfaces for Hyperbolic Knot
No full textGiven a link L in the 3-sphere, one can build simplicial complexes MS(L) and IS(L), called the Kakimizu complexes. These complexes have isotopy classes of minimal genus and incompressible Seifert surfaces for L as their vertex sets and have simplicial structures defined via a disjointness property. The Kakimizu complexes enjoy many topological properties and are conjectured to be contractible. Following the work of Gabai on sutured manifolds and Murasugi sums, MS(L) and IS(L) have been classified for various classes of links. This thesis focuses on hyperbolic knots; using minimal surface representatives and Kakimizu's formulation of the path-metric on MS(K), we are able to bound the diameter of this complex in terms of only the genus of the knot. The techniques of this paper are also generalized to one-cusped manifolds with a preferred relative homology class
Seifert manifolds and (1,1)-knots
No full textThe aim of this paper is to investigate the relations between Seifert manifolds and (1,1)-knots. In particular, we prove that each orientable Seifert manifold with invariants{Oo,0| -1; (p,q),..., (p,q),(l, l-1)}, where (p,q) are taken n times, has a cyclically presented fundamental group and, moreover, it is the n-fold strongly-cyclic covering of the lens space L(|nlq - p|, q), branched over a suitable (1,1)-knot
Our pioneers: Martin L. Ensign
No full textTranscript of a newspaper article in The Box Elder News, issue of Sept. 1, 1910, about Martin L. Ensign, a pioneer born in Massachusetts in 1831 who settled in Brigham City in 1853. Copied by Kenneth L. Seifert in 193
Lasius nigroemarginatus Forel, 1874 is a F1 Hybrid between L. emarginatus (Olivier, 1792) and L. platythorax Seifert, 1991 (Hymenoptera, Formicidae)
No full textEs wird gezeigt, dass der in neueren taxonomischen Katalogen als jüngeres Synonym von Lasius emarginatus (Olivier, 1792) gelistete Lasius nigroemarginatus Forel, 1874 ein F1-hybrid zwischen L. emarginatus und L. platythorax Seifert, 1991 ist. Diese Schlussfolgerung ergab sich aus der Position von vier Typusexemplaren von L. nigroemarginatus in dem durch 16 kontinuierliche phenotypische Merkmale charakterisierten Vektorraum der drei möglichen Elternarten. Diese waren im Untersuchungsmaterial vertreten durch 144 Arbeiterinnen von Lasius niger (Linnaeus, 1758), 90 Arbeiterinnen von L. emarginatus und 94 Arbeiterinnen von L. platythorax – wobei das Material aus dem gesamten paläarktischen Verbreitungsgebiet der betrachteten Arten stammte. Sowohl eine Nichtmetrische Multidimensionale Skalierung als auch ein hypothesenfreies (wild-card) Rechnen in einer linearen Diskriminanzanalyse platzierte die Typusexemplare zwischen den Clustern von L. emarginatus und L. platythorax und weit entfernt vom Cluster von Lasius niger. Eine gesonderte Betrachtung der Struktur- und Pigmentmerkmale zeigt, dass die Typen von L. nigroemarginatus in fünf Merkmalen ideal intermediär zwischen L. emarginatus und L. platythorax, in vier Merkmalen näher zu L. emarginatus und in sieben Merkmalen näher zu L. platythorax positioniert waren. Die aus der Position im morphologischen Raum abgeleiteten Schlussfolgerungen werden durch Daten zu Schwarmzeiten und Mikrohabitatwahl sowie den durch Forel beim Öffnen des Nestes wahrgenommenen Geruch bestätigt. Lasius niger konnte klar als Elternart ausgeschlossen werden. Es wird darauf hingewiesen, dass der Internationale Code für Zoologische Nomenklatur (ICZN) logische Inkonsistenzen und Definitionsschwächen bezüglich der Behandlung von echten hybridogenen Arten aufweist und dass die Artikel 1.3.3, 17.2 und 23.8 des ICZN geändert oder neugeschrieben werden sollten.Lasius nigroemarginatus Forel, 1874, that has been synonymized in recent catalogues with Lasius emarginatus (Olivier, 1792), is shown to represent a F1 hybrid between L. emarginatus and L. platythorax Seifert, 1991. This conclusion was firstly drawn from numeric description of 16 phenotypic characters and the placement of four type workers of L. nigroemarginatus within vectorial space of the three possible parental species. These were represented by 144 workers of Lasius niger (Linnaeus, 1758), 90 workers of L. emarginatus and 94 workers of L. platythorax – with a coverage for all species by their whole Palaearctic range. The type sample was placed intermediate between (and clearly separated from) the clusters of L. emarginatus and L. platythorax in both Nonmetric Multidimensional Scaling and when run as a wild-card in a three-class linear discriminant analysis. Comparing structural and pigmentation characters one by one, the types of L. nigroemarginatus were intermediate between L. emarginatus and L. platythorax in five characters, closer to L. emarginatus in four characters and closer to L. platythorax in seven characters. The conclusions derived from the position in the morphological space were supported by data on swarming time and nest habitat selection and the odor perceived by the collector Forel. Lasius niger could be clearly excluded to represent a parental species. It is argued that the International Code of Zoological Nomenclature (ICZN) shows logical inconsistencies and explanatory weakness regarding the treatment of truly hybridogenous species and that the Articles 1.3.3, 17.2 and 23.8 of ICZN should be amended or re-written
Life and experiences of George Washington Nichols
No full textTypescript of an account of some anecdotes from the life of George Washington Nichols (born 1859) of Salt Lake City. Author unknown; transcribed by Kenneth L. Seifert of Brigham City, April 25, 193
The effect of diet and temperature on life‐history traits and sexual size dimorphism in a capital‐breeding moth
No full textAbstract In insects, temperature and diet quality during larval development are two fundamental factors affecting key life history traits that, in turn, determine an individuals' fitness. Life‐history theory predicts that within species, individuals attain larger sizes when developing under colder temperatures (i.e., temperature—size rule) or on high‐quality diet (i.e., allowing for more effective resource acquisition and development). Here, I studied how temperature and host‐plant identity affect growth rate, larval development time and size at maturity in Aglia tau L. (Lepidoptera: Saturniidae: Agliinae), a univoltine capital breeding moth. I further examined whether and to what extent these environmental variables influence the degree of sexual size dimorphism. Caterpillars were reared under two contrasting temperature regimes (constantly 18 and 23°C) and fed with three natural host plants, that is, Carpinus betulus L. (Betulaceae), Fagus sylvatica L. (Fagaceae) and Prunus padus L. (Rosaceae). A full‐factorial analysis of variance design was used to test for effects of temperature and host identity on life history traits and to account for possible interactive effects. Contrary to theory, the body sizes of males and females were maintained at higher temperatures or even increased when reared on the highest quality host plant ( Prunus padus ). As predicted, the high‐quality host allowed for overall larger body sizes in both sexes and further resulted in a higher degree of sexual size dimorphism. The study highlights the need to account for diet effects when studying temperature‐induced life history responses in insects and to consider further traits that may influence species‐specific reaction norms
Seifert manifolds that are ramified two-sheeted cyclic coverings. (Spanish)
No full textIf L is a link in the 3-sphere S3, let e:L˜→S3 denote the 2-fold cyclic covering of S3 branched over L. R. H. Fox [Rev. Mat. Hisp.-Amer. (4) 32 (1972), 158–166;] has shown that there is no link L in S3 such that L˜ is S1×S1×S1; the author [ibid. (4) 33 (1973), 32–35] has extended this to Fg×S1 (g≥1), where Fg denotes a closed orientable surface of genus g. In the present article he investigates the following more general question: Given any orientable Seifert fibre space M, determine whether M is homeomorphic to L˜ for some link L⊂S3; if the answer is yes, describe L.
He finds an affirmative answer for all orientable Seifert fibre spaces over a 2-sphere or over a nonorientable closed surface as base B. In these cases a corresponding link L is constructed by using the technique of tangle modification introduced by J. H. Conway [Computational problems in abstract algebra (Proc. Conf., Oxford, 1967), pp. 329–358, Pergamon, Oxford, 1970;], to which corresponds the operation of removing from L˜ a solid torus and sewing it back differently in the covering. For orientable base B of positive genus g, i.e., B=Fg (g≥1), the situation is more complex: (i) The author finds a negative answer to the above question for the fibre spaces (Oog|b) without exceptional fibres, provided b≠±1,±2 and g≥1 (for the notation, see H. Seifert's article [Acta Math. 60 (1933), 147–238; Zbl 6, 83]). (ii) Analyzing the special assumption that the unique nontrivial covering transformation of the 2-fold cover is fibre-preserving, the author obtains a list of Seifert fibre spaces with base Fg, each of which is homeomorphic to L˜ for an appropriate link L in S3. (iii) The verification that this list is complete would depend on an affirmative answer to an unsolved question concerning involutions in Seifert fibre spaces. (iv) Modifying the main question, the author proves that each orientable Seifert fibre space over Fg (g≥0) is a 2-fold cyclic cover branched over a link of Hg, the 3-sphere with g handles attached.
Finally, it is shown how some of these results extend from the class of Seifert fibre spaces to the class of "graph-manifolds'' introduced by F. Waldhausen [Invent. Math. 3 (1967), 308–333; ibid. 4 (1967), 87–117;]. The paper is a fine piece of geometry, being specified throughout with interesting examples.Depto. de Álgebra, Geometría y TopologíaFac. de Ciencias MatemáticasTRUEpu
The L 2 -Alexander torsion for Seifert fiber spaces
No full textWe calculate the L-2-Alexander torsion for Seifert fiber spaces and graph manifolds in terms of the Thurston norm
Life of John D. Burt
No full textTypescript of a biographical sketch of John D. Burt, from a 1906 article in the Box Elder News, copied by Kenneth L. Seifert of Brigham City in 1939. John D. Hurt was born in Scotland in 1827 and the family came to Utah in 1851, settling at Brigham City by 1855. Typed by Kenneth L. Seifert in 193
Cardiocondyla littoralis Seifert 2003
No full text<i>Cardiocondyla littoralis</i> Seifert 2003 [types investigated] <p>This species has been described from SE Kazakhstan. Investigated were the holotype worker and 11 worker paratypes, all labelled “KAZ: 46.41.57 N, 80.35.00 E, 358 m, W-Ufer des Sassy Kol, Lössboden, versalzt, hart, selten überschwemmt leg. Seifert 2001.08.07 -1”, SMN Goerlitz.</p> <p> <b>All material examined</b>. Numeric phenotypical data were taken in five workers of the type sample from Kazakhstan. For details see supplementary information SI1, SI2..</p> <p> <b>Geographic range</b>. Only known from the type locality (46.6992 °N, 80.5833 °E, 356 m).</p> <p> <b>Diagnosis</b>: --Worker (Tab. 2, Figs. 26–29, key). Small, CS 486 µm. Head moderately elongated, CL/CW 1.167. Postocular distance much larger than in <i>C. ulianini</i> and <i>C. caspiense</i> <b>n. sp.</b> PoOc/CL 0.442. Scape shorter, SL/CS 0.792. Eye rather large, EYE/CS 0.249. Occiput in dorsal aspect with evenly rounded corners, its median third straight or weakly concave. Frons moderately broad (FRS/CS 0.241), frontal carinae slightly converging immediately caudal of FRS level (FL/FR 1.044). Dorsal profile of promesonotum and of propodeum convex with a well-developed metanotal depression (MGr/CS 3.70 %). Propodeal spines very short (SP/CS 0.087, more triangular but with sharp tips), their axis in profile deviating by about 48° from longitudinal axis of mesosoma, their bases much approached (SPBA/CS 0.223). Petiole narrow and lower than in <i>C. ulianini</i> but still higher than wide (PeW/CS 0.274, PeH/ CS 0.306), its node in dorsal aspect as long as wide, tapering frontad; in lateral aspect its frontodorsal profile not concave, more directed caudad (about 50° relative to ventral profile). Postpetiole much narrower than in <i>C. ulianini</i>, less than twice as wide as high (PpW/CS 0.500, PpH/CS 0.277), in dorsal view heard-shaped, with a concave anterior margin and convex sides; postpetiolar sternite with a shallow anteromedian bulge. Clypeus between the level of the paramedian 1st order setae, smooth, its anteromedian margin straight or weakly concave. Frontal laminae and a small area posterior of them finely and densely longitudinally rugulose. Anteromedian vertex glabrous and whole vertex without longitudinal microsculpture, in overall impression similar to situation in <i>C. ulianini</i>, foveolar interspaces glabrous and on the average as wide as foveolar diameter (dFOV 13–16), the interspaces with scattered very fine stickman-like fragments of a microreticulum, internal foveolar surface often with longitudinal carinulae (Fig. 29). Dorsal mesosoma in overall impression shiny; dorsal promesonotum with shallow foveolae of 9–16 µm diameter, interspaces clearly wider than foveolar diameter; dorsal propodeum shiny but very finely microrugulose-reticulate. Caudolateral pronotum, ventrolateral mesonotum, mesopleuron, and propodeum below spiracular level finely reticulate. Lateral metapleuron with 2–4 curved longitudinal carinae. Waist segments almost smooth and shining. First gaster tergite glabrous. Pubescence on whole body rather long but dilute, PLG/CS 6.90 %, sqPDG 4.63. Color of head, mesosoma, femora, and gaster dark brown; waist segments sometimes slightly lighter with yellowish tinge.</p> <p> <b>Taxonomic comments and clustering results</b>. The taxonomic separation of <i>Cardiocondyla littoralis</i> from those of sympatric <i>C. ulianini</i> and <i>C. caspiense</i> <b>n. sp.</b> is supported by a PCA considering the characters PoOc/CL, Pew/CS, PpH/CS and PLG/CS (Fig. 136). The type specimens clearly differed from syntopic <i>ulianini</i> by the much larger PoOc/CL, larger PeW/PpW, a lower petiole with a less steep anterior slope, and by shorter spines. <i>C. littoralis</i> shows some similarity to the W Palaearctic <i>gallilaeica</i> from which it differs by the much larger PoOc/CL and PeW/PpW, the more excavated dorsofrontal postpetiolar margin, the almost straight median third of occipital margin, and the wider frons with more curved frontal carinae.</p> <p> <b>Biology.</b> The workers were collected when foraging on the surface of a salty loess soil with very sparse vegetation near the margin of a lake in a semidesert.</p>Published as part of <i>Seifert, Bernhard, 2023, A revision of the Palaearctic species of the ant genus Cardiocondyla Emery 1869 (Hymenoptera: Formicidae), pp. 1-64 in Zootaxa 5274 (1)</i> on page 34, DOI: 10.11646/zootaxa.5274.1.1, <a href="http://zenodo.org/record/7888156">http://zenodo.org/record/7888156</a>
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