Sökning: "Families of cycles"
Visar resultat 1 - 5 av 6 avhandlingar innehållade orden Families of cycles.
1. Families of cycles and the Chow scheme
Sammanfattning : The objects studied in this thesis are families of cycles on schemes. A space — the Chow variety — parameterizing effective equidimensional cycles was constructed by Chow and van der Waerden in the first half of the twentieth century. Even though cycles are simple objects, the Chow variety is a rather intractable object. LÄS MER
2. Snarks : Generation, coverings and colourings
Sammanfattning : For a number of unsolved problems in graph theory such as the cycle double cover conjecture, Fulkerson's conjecture and Tutte's 5-flow conjecture it is sufficient to prove them for a family of graphs called snarks. Named after the mysterious creature in Lewis Carroll's poem, a \emph{snark} is a cyclically 4-edge connected 3-regular graph of girth at least 5 which cannot be properly edge coloured using three colours. LÄS MER
3. Adolescent pregnancies in Nicaragua. The importance of education
Sammanfattning : Early adolescent pregnancy implies increased social and medical risks. There is lack of understanding of the mechanisms behind early sexual debut and pregnancy. This contributes to the difficulties to meet the educational and health care needs of adolescents. LÄS MER
4. Modelling macroeconomic time series with smooth transition autoregressions
Sammanfattning : Among the parametric nonlinear time series model families, the smooth transition regression (STR) model has recently received attention in the literature. The considerations in this dissertation focus on the univariate special case of this model, the smooth transition autoregression (STAR) model, although large parts of the discussion can be easily generalised to the more general STR case. LÄS MER
5. Atom probe tomography of Zircaloy-2 exposed to boiling water reactor operation
Sammanfattning : Zirconium alloys are used as cladding tubes for the fuel in nuclear reactors. In boiling water reactors (BWRs), the alloy Zircaloy-2, which contains the alloying elements Sn, Fe, Cr, Ni, and O, is commonly used. LÄS MER