Szasz [l ] has recently shown that a group is cyclic if and only if it satisfies condition (A) below. (A) Every cyclic subgroup of the group is for some positive integer k the subgroup generated by the £th powers of the elements of the group. We shall extend this idea here to show that a metacyclic group whose commutator subgroup has order relatively prime to its index is characterized as a sol...

Special covers are metacyclic covers of the projective line, with Galois group Z/p ⋊ Z/m, which have a specific type of bad reduction to characteristic p. Such covers arise in the study of the arithmetic of Galois covers of P with three branch points. Our results provide a classification of all special covers in terms of certain lifting data in characteristic p.

The obligate intracellular protozoan, Leishmania infantum chagasi (Lic) is the causative agent of visceral leishmaniasis in South America. The flagellated promastigote life stage of the parasite undergoes receptor-mediated phagocytosis by macrophages. This process is followed by a transient delay in phagolysosome maturation that allows for conversion into the amastigotes, a stage that is resist...

Transmission experiments were conducted to compare the transmissibility of genetically different Trypanosoma congolense (Savannah subgroup) strains isolated from cattle in a trypanosomiasis endemic area of eastern Zambia. A total of 17 strains were compared. Three strains were extremely virulent with a short pre-patent period, high parasitaemia and a short median survival time (between 5 and 9 ...

A member of the Trypanosoma cruzi gp82 family, expressed on metacyclic trypomastigote surface and identified by monoclonal antibody (MAb) 3F6, plays a key role in host cell invasion. Apart from the gp82 defined by MAb 3F6, no information is available on members of this protein family. From cDNA clones encoding gp82 proteins sharing 59.1% sequence identity, we produced the recombinant proteins J...

Groups of cattle were inoculated intravenously with cloned populations of bloodstream forms of Trypanosoma brucei or Trypanosoma congolense. All five steers infected with T. brucei ILTat 2.1 and six of the eight steers infected with T. congolense IL 13-E14 became aparasitemic within 16 and 32 weeks postinfection, respectively. Examination of sera from animals infected with T. brucei by indirect...

The in vitro metacyclogenesis of a visceral (VL) and cutaneous (CL) human strain of Leishmania infantum was monitored in order to find out the kinetics of this process and the in vitro infective capacity for macrophages of the metacyclic promastigotes developed. To identify, enumerate, and separate the metacyclic population, the complement-dependent lysis by normal serum and the agglutination b...

We compute the stable reduction of some Galois covers of the projective line branched at three points. These covers are constructed using Hurwitz spaces parameterizing metacyclic covers. The reduction is determined by a certain hypergeometric differential equation. This generalizes the result of Deligne and Rapoport on the reduction of the modular curve X (p).

For a number field k, let k1 denote its Hilbert 2-class field, and put k2 = (k1)1. We will determine all imaginary quadratic number fields k such that G = Gal(k2/k) is abelian or metacyclic, and we will give G in terms of generators and relations.