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The centers and cyclic radicals of generalized Baumslag–Solitar groups (GBS-groups) are studied. Criteria for their non-triviality are found and an algorithm to compute the center and cyclic radical is given. In addition, for each unimodular GBS-group, a GBS-cover, i.e., a GBS-group in whose underlying graph the weights around each vertex are constant in absolute value, is constructed. These groups are then characterized by a minimality property.

For a large class of groups necessary and sufficient conditions are given for their group algebras to have the bounded splitting property.

A new technique for probing the structural rearrangements of molecules following ionization has recently been demonstrated. Whilst straightforward to implement, this technique offers remarkable time resolution, allowing intramolecular nuclear dynamics to be followed with a precision of 100 as. Here we discuss this technique, termed PACER (probing attosecond dynamics by chirp encoded recollision), examine the processes that affect the measurement, and compare the technique to alternative methods for probing vibrational wavepackets in light molecules.

We study the structure of groups that satisfy the maximal conditions on infinite normal subgroups and the minimal condition on normal subgroups of infinite index. Characterizations of both properties are given in the general case. In addition, detailed information is obtained about the structure of soluble groups that satisfy these chain conditions.

Recently, we have demonstrated that administration of metyrapone, to suppress cortisol synthesis and decrease negative feedback at the pituitary, results in an increase in circulating ACTH and adrenal growth in the late gestation sheep fetus. In these studies, we demonstrated a 2-fold increase in adrenocortical growth using morphometric techniques. To elucidate the potential molecular mechanisms leading to the increase in adrenal growth, we examined adrenal expression of the cell cycle regulatory proteins (cyclin D1) and cyclin-kinase inhibitory proteins (p16ink, p21Cip), and insulin-like growth factor-II (IGF-II), IGF-binding protein 2 (IGFBP-2) and IGF-I type 1 Receptor (IGF1R) from fetuses infused with metyrapone or vehicle for 15 days. There was a significant decrease in adrenal expression of cyclin D1 in metyrapone-(472.0 +/- 29.7) compared with vehicle-infused (662.7 +/- 29.2) fetuses. There was no significant difference, however, in the adrenal expression of the cyclin-kinase inhibitory proteins (p16ink or p21Cip) or in the IGF system (IGF-II, IGFBP-2 or IGF1R) mRNA between metyrapone- and vehicle-infused. In summary, in this model of metyrapone-activated adrenal cortical hypertrophy, growth occurs with a suppression of the rate-limiting cell cycle protein and without activation of the IGF system.

A complete classification is given of all groups G with the property that every automorphism centralizes a subgroup with prime index in G.

Let n be an integer greater than 1, and let G be a group. A subset {x1, X2, ..., xn} of n elements of G is said to be rewritable if there are distinct permutations π and σ of {1,2, …, n} such that The group G is said to have the rewriting property Qn or to be n-rewritable, if every subset of n elements of G is rewritable. The main result of this paper shows that the only nontrivial semlsimple groups with the property Q5 are the alternating group A5, the symmetric group S5, the projective special linear group PSL(2, 7) and the projective general linear group PGL(2, 7)

Saccharomyces cerevisiae strains carrying vps18 mutations are defective in the sorting and transport of vacuolar enzymes. The precursor forms of these proteins are missorted and secreted from the mutant cells. Most vps18 mutants are temperature sensitive for growth and are defective in vacuole biogenesis; no structure resembling a normal vacuole is seen. A plasmid complementing the temperature-sensitive growth defect of strains carrying the vps18-4 allele was isolated from a centromere-based yeast genomic library. Integrative mapping experiments indicated that the 26-kb insert in this plasmid was derived from the VPS18 locus. A 4-kb minimal complementing fragment contains a single long open reading frame predicted to encode a 918-amino-acid hydrophilic protein. Comparison of the VPS18 sequence with the PEP3 sequence reported in the accompanying paper (R. A. Preston, H. F. Manolson, K. Becherer, E. Weidenhammer, D. Kirkpatrick, R. Wright, and E. W. Jones, Mol. Cell. Biol. 11:5801-5812, 1991) shows that the two genes are identical. Disruption of the VPS18/PEP3 gene (vps18 delta 1::TRP1) is not lethal but results in the same vacuolar protein sorting and growth defects exhibited by the original temperature-sensitive vps18 alleles. In addition, vps18 delta 1::TRP1 MAT alpha strains exhibit a defect in the Kex2p-dependent processing of the secreted pheromone alpha-factor. This finding suggests that vps18 mutations alter the function of a late Golgi compartment which contains Kex2p and in which vacuolar proteins are thought to be sorted from proteins destined for the cell surface. The Vps18p sequence contains a cysteine-rich, zinc finger-like motif at the COOH terminus. A mutant in which the first cysteine of this motif was changed to serine results in a temperature-conditional carboxypeptidase Y sorting defect shortly after a shift to nonpermissive conditions. We identified a similar cysteine-rich motif near the COOH terminus of another Vps protein, the Vps11/Pep5/End1 protein. Preston et al. (Mol. Cell. Biol. 11:5801-5812, 1991) present evidence that the Vps18/Pep3 protein colocalizes with the Vps11/Pep5 protein to the cytosolic face of the vacuolar membrane. Together with the similar phenotypes exhibited by both vps11 and vps18 mutants, this finding suggests that they may function at a common step during vacuolar protein sorting and that the integrity of their zinc finger motifs may be required for this function.

The characterization of rapidly solidified powders, their extrusion, and the evaluation of mechanical properties of the extrudates have been carried out for an Al–5Fe–7 Mn alloy. In the atomized powder, a metastable non–stoichiometric phase has been identified which transforms to the equilibrium (FeMn)Al6 phase on heating at elevated temperatures (