Two magnetic regimes in doped ZnO corresponding to a dilute magnetic semiconductor and a dilute magnetic insulator.

Films of ZnO doped with magnetic ions Mn and Co and, in some cases, with Al have been fabricated with a very wide range of carrier densities. Ferromagnetic behavior is observed in both insulating and metallic films, but not when the carrier density is intermediate. Insulating films exhibit variable range hopping at low temperatures and are ferromagnetic at room temperature due to the interaction of the localized spins with static localized states. The magnetism is quenched when carriers in the localized states become mobile. In the metallic (degenerate semiconductor) range, robust ferromagnetism reappears together with very strong magneto-optic signals and room temperature anomalous Hall data. This demonstrates the polarization of the conduction bands and indicates that, when ZnO is doped into the metallic regime, it behaves as a genuine magnetic semiconductor.

Room-temperature magneto-optics of ferromagnetic transition-metal-doped ZnO thin films.

Magneto-optic studies of ZnO doped with transition metals Co, Mn, V, and Ti indicate a significant magnetic circular dichroism (MCD) at the ZnO band edge at room temperature, together with an associated dispersive Faraday rotation. Similar spectra occur for each dopant, which implies that the ferromagnetism is an intrinsic property of the bulk ZnO lattice. At 10 K, additional paramagnetic contributions to the MCD are observed, but above about 150 K, the magnitude of the MCD signal is dominated by the ferromagnetism and is almost temperature independent. The MCD at the ZnO band edge shows room temperature hysteretic behavior.

Lectins from indigenous Australian wildflowers--detection of lectins from Bauhinia carronii, Hardenbergia comptoniana, Ptilotis obovatus and Rhadogia crassifolia.

Extracts from 21 indigenous Australian plant species, representing eight genera, were tested for haemagglutinating activity to human and animal erythrocytes. Extracts from Bauhinia carronii, Hardenbergia comptoniana, Ptilotis obovatus and Rhadogia crassifolia agglutinated at least one of the erythrocyte types tested. The extracts from B. carronii and R. crassifolia contained mitogens for human lymphocytes. Both the haemagglutinating and mitogenic activity of the B. carronii extract were inhibited by lactose. Both the haemagglutinating and mitogenic activity of R. crassifolia were inhibited by maltose and alpha-methyl-glucoside. The haemagglutinating activity of H. comptoniana was inhibited by raffinose and the haemagglutinating activity of P. obovatus by maltose and alpha-methylglucoside.

Regulatory policy and abortion clinics: implications for planning.

The practicalities of formulating regulatory policy associated with elective abortion often place public health officials at the center of political controversy. Resulting conflicts can inhibit a rational consideration of long-term objectives in implementing a national policy which assures legal accessibility to all who would select abortion as an alternative to term birth. Regulation which uses primarily structural criteria for monitoring and evaluating services tends to de-emphasize the importanc of contraceptive counseling as a component of abortion services. Our process/outcome evaluation of abortion clinics located in Chicago suggests that contraceptive counseling provided at the time of the abortion procedure has a potential long-term impact in terms of reducing the need for elective abortion. We suggest that regulation policy should include process and outcome criteria which support the eventual reduction in need for abortion as a long-range policy goal and suggest key issues for consideration when such a policy is formulated.