Pressure Induced Charge Disproportionation in LaMnO3_{3}

We present a total energy study as a function of volume in the cubic phase of LaMnO$_{3}$. A charge disproportionated state into planes of Mn$^{3+}$O$_{2}$/Mn$^{4+}$O$_{2}$ was found. It is argued that the pressure driven localisation/delocalisation transition might go smoothly through a region of Mn$^{3+}$ and Mn$^{4+}$ coexistence.Comment: 3 pages, 1 figure, Conference Proceedings: Nanospintronics: Design and Realization (Kyoto, Japan 24-28 May, 2004

Comment on "Systematics of the Induced Magnetic Moments in 5d Layers and the Violation of the Third Hund's Rule"

Comment on F. Wilhelm et al., Phys. Rev. Lett. 87, 207202 (2001)Comment: 1 pag

Necrotrophic growth of legionella pneumophila

This study examined whether Legionella pneumophila is able to thrive on heat-killed microbial cells (necrotrophy) present in biofilms or heat-treated water systems. Quantification by means of plate counting, real-time PCR, and flow cytometry demonstrated necrotrophic growth of L. pneumophila in water after 96 h, when at least 100 dead cells are available to one L. pneumophila cell. Compared to the starting concentration of L. pneumophila, the maximum observed necrotrophic growth was 1.89 log units for real-time PCR and 1.49 log units for plate counting. The average growth was 1.57 ± 0.32 log units (n = 5) for real-time PCR and 1.14 ± 0.35 log units (n = 5) for plate counting. Viability staining and flow cytometry showed that the fraction of living cells in the L. pneumophila population rose from the initial 54% to 82% after 96 h. Growth was measured on heat-killed Pseudomonas putida, Escherichia coli, Acanthamoeba castellanii, Saccharomyces boulardii, and a biofilm sample. Gram-positive organisms did not result in significant growth of L. pneumophila, probably due to their robust cell wall structure. Although necrotrophy showed lower growth yields compared to replication within protozoan hosts, these findings indicate that it may be of major importance in the environmental persistence of L. pneumophila. Techniques aimed at the elimination of protozoa or biofilm from water systems will not necessarily result in a subsequent removal of L. pneumophila unless the formation of dead microbial cells is minimized

Mott Transition of MnO under Pressure: Comparison of Correlated Band Theories

The electronic structure, magnetic moment, and volume collapse of MnO under pressure are obtained from four different correlated band theory methods; local density approximation + Hubbard U (LDA+U), pseudopotential self-interaction correction (pseudo-SIC), the hybrid functional (combined local exchange plus Hartree-Fock exchange), and the local spin density SIC (SIC-LSD) method. Each method treats correlation among the five Mn 3d orbitals (per spin), including their hybridization with three O $2p$ orbitals in the valence bands and their changes with pressure. The focus is on comparison of the methods for rocksalt MnO (neglecting the observed transition to the NiAs structure in the 90-100 GPa range). Each method predicts a first-order volume collapse, but with variation in the predicted volume and critical pressure. Accompanying the volume collapse is a moment collapse, which for all methods is from high-spin to low-spin (5/2 to 1/2), not to nonmagnetic as the simplest scenario would have. The specific manner in which the transition occurs varies considerably among the methods: pseudo-SIC and SIC-LSD give insulator-to-metal, while LDA+U gives insulator-to-insulator and the hybrid method gives an insulator-to-semimetal transition. Projected densities of states above and below the transition are presented for each of the methods and used to analyze the character of each transition. In some cases the rhombohedral symmetry of the antiferromagnetically ordered phase clearly influences the character of the transition.Comment: 14 pages, 9 figures. A 7 institute collaboration, Updated versio

Prevalence of sexually transmitted infections in women attending antenatal care in Tete province, Mozambique

Objective. To determine the prevalence of Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and syphilis in pregnant women. Methods. A cross-sectional study was conducted among women attending antenatal care clinics (ANCs). Blood samples were tested for syphilis using the rapid plasma reagin (RPR) and treponemal haemagglutination (TPHA) tests; CT and NG were diagnosed using a manual polymerase chain reaction assay on first-void urine samples. A socio-demographic questionnaire was completed. Results were compared with previous published data on sexually transmitted infection (STI) prevalence in Mozambique. Results. Blood and urine samples were collected from 1 119 and 835 women, respectively. The prevalence of CT was 4.1%, and that of NG 2.5%. The RPR test was positive in 5.2% of the women, and 7.1% had a positive TPHA test. Active syphilis was found in 4.7%. In univariate analysis, CT was associated with having had any level of education (