Evaluation of a Number of Grass Species for Restoring Degraded Semi-Arid Rangelands in Southern Africa

The biophysical environment is an important determinant of land degradation in both commercial and communal land tenure systems in South Africa. According to a recent study on the status of land degradation, approximately 25% of the total land cover in South Africa is degraded. Several technologies exist to restore the soil and vegetation degraded areas in natural pastures. To improve the production and biodiversity potential for agricultural and conservation uses in these rangelands, a common restoration technology includes the cultivation the eroded and compacted soil surfaces by rip- ploughing and the re-vegetation with high productive, palatable and perennial species. Five grasses, Chloris gayana, Digitaria eriantha, Anthephora pubescens, Cenchrus ciliaris and Panicum maximum, were used in over-sowing trials in an semi-arid region with two types of soils, to evaluate their effectiveness to restore the degraded natural pasture. Results show that D. eriantha, C. gayana and P. maximum should be used in an over-sowing treatment to restore high clay or silt soil types, whereas A. pubescens and C. ciliaris are more suitable for sandy soils. The diversity in areas which were only rip-ploughed also increased considerably with palatable, perennial species such as Themeda triandra, Setaria sphacelata and Eragrostis curvula

Specificity Between Lactobacilli And Hymenopteran Hosts Is The Exception Rather Than The Rule

Lactobacilli (Lactobacillales: Lactobacillaceae) are well known for their roles in food fermentation, as probiotics, and in human health, but they can also be dominant members of the microbiota of some species of Hymenoptera (ants, bees, and wasps). Honey bees and bumble bees associate with host-specific lactobacilli, and some evidence suggests that these lactobacilli are important for bee health. Social transmission helps maintain associations between these bees and their respective microbiota. To determine whether lactobacilli associated with social hymenopteran hosts are generally host specific, we gathered publicly available Lactobacillus 16S rRNA gene sequences, along with Lactobacillus sequences from 454 pyrosequencing surveys of six other hymenopteran species (three sweat bees and three ants). We determined the comparative secondary structural models of 16S rRNA, which allowed us to accurately align the entire 16S rRNA gene, including fast-evolving regions. BLAST searches and maximum-likelihood phylogenetic reconstructions confirmed that honey and bumble bees have host-specific Lactobacillus associates. Regardless of colony size or within-colony oral sharing of food (trophallaxis), sweat bees and ants associate with lactobacilli that are closely related to those found in vertebrate hosts or in diverse environments. Why honey and bumble bees associate with host-specific lactobacilli while other social Hymenoptera do not remains an open question. Lactobacilli are known to inhibit the growth of other microbes and can be beneficial whether they are coevolved with their host or are recruited by the host from environmental sources through mechanisms of partner choice.National Science Foundation PRFB-1003133, DEB-0919519Texas Higher Education Coordinating Board 01923, National Institutes of Health GM067317Integrative BiologyCellular and Molecular BiologyCenter for Computational Biology and BioinformaticsBrackenridge Field Laborator

U.S. Radio in the 21st Century: Staying the Course in Unknown Territory

This essay examines the development of the radio industry in the United States as it makes its way into the 21st century. Issues of regulation, technology, commerce, and culture are addressed

Processing and Transmission of Information

Contains reports on three research projects

New optical polarization measurements of the Crab pulsar

The Crab nebula and its pulsar have been observed for about 3 hours with the high-speed photo-polarimeter OPTIMA in January 2002 at the Calar Alto 3.5m telescope. The Crab pulsar intensity and polarization are determined at all phases of rotation with higher statistical accuracy than ever. Therefore, we were able to separate the so-called 'off-pulse' phase emission (with an intensity of about 1.2% compared to the main peak, assumed to be present at all phases) from the pulsed emission and show the 'net' polarization of the pulsed structures. Recent theoretical results indicate that the measured optical polarization of the Crab pulsar is similar to expectations from a two-pole caustic emission model or a striped pulsar wind model.Comment: AIP Conference Proceedings "Astrophysical Sources of High Energy Particles and Radiation", eds. T. Bulik et al. (NY:AIP), Volume 801, 2005, pp. 306-31

Media events, spectacles and risky globalization: a critical review and possible avenues for future research

We review the research conducted to date on media events and media spectacles. We posit that the main phenomena challenging the current conceptualizations of media event and media spectacle are (1) the understanding of risk, (2) the context of disasters and (3) globalization and the mediation of news in the context of transnational and transitional societies. We suggest that more research on disruptive events is needed. In the context of the new media landscape in particular, the ritual researcher may need to take into account the concepts of temporality and unpredictability as inherent features of media events and rituals – the traumatic events researcher may benefit from the concept of global risk society. Finally, we argue that more research needs to be carried out on transitional societies, as we need to learn more about the role of mediation, events and spectacles in democratization processes and in contemporary revolutions. Overall, our findings indicate that in the context of global risk society, constant disruptions and unplanned events, together with the changes in news transmission, need to be taken as a starting point also in the research frames used to understand the mediation of events in contemporary society