Fast fluorescence techniques for crystallography beamlines

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86817/1/S0021889811016748.pd

Synthesis Paper: Targeted Livestock Grazing: Prescription for Healthy Rangelands

Targeted livestock grazing is a proven tool for manipulating rangeland vegetation, and current knowledge about targeted livestock grazing is extensive and expanding rapidly. Targeted grazing prescriptions optimize the timing, frequency, intensity, and selectivity of grazing (or browsing) in combinations that purposely exert grazing/browsing pressure on specific plant species or portions of the landscape. Targeted grazing differs from traditional grazing management in that the goal of targeted grazing is to apply defoliation or trampling to achieve specific vegetation management objectives, whereas the goal of traditional livestock grazing management is generally the production of livestock commodities. A shared aim of targeted livestock grazing and traditional grazing management is to sustain healthy soils, flora, fauna, and water resources that, in turn, can sustain natural ecological processes (e.g., nutrient cycle, water cycle, energy flow). Targeted grazing prescriptions integrate knowledge of plant ecology, livestock nutrition, and livestock foraging behavior. Livestock can be focused on target areas through fencing, herding, or supplement placement. Although practices can be developed to minimize the impact of toxins contained in target plants, the welfare of the animals used in targeted grazing must be a priority. Monitoring is needed to determine if targeted grazing is successful and to refine techniques to improve efficacy and efficiency. Examples of previous research studies and approaches are presented to highlight the ecological benefits that can be achieved when targeted grazing is applied properly. These cases include ways to suppress invasive plants and ways to enhance wildlife habitat and biodiversity. Future research should address the potential to select more adapted and effective livestock for targeted grazing and the associated animal welfare concerns with this practice. Targeted livestock grazing provides land managers a viable alternative to mechanical, chemical, and prescribed fire treatments to manipulate rangeland vegetation

Global urban environmental change drives adaptation in white clover

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

The first spectroscopic model for the S1 state multiline signal of the OEC

AbstractThe parallel-mode electron paramagnetic resonance (EPR) spectrum of the S1 state of the oxygen-evolving complex (OEC) shows a multiline signal centered around g=12, indicating an integer spin system. The series of [Mn2(2-OHsalpn)2] complexes were structurally characterized in four oxidation levels (MnII2, MnIIMnIII, MnIII2, and MnIIIMnIV). By using bulk electrolysis, the [MnIIIMnIV(2-OHsalpn)2(OH)] is oxidized to a species that contains MnIV oxidation state as detected by X-ray absorption near edge spectroscopy (XANES) and that can be formulated as MnIV4 tetramer. The parallel-mode EPR spectrum of this multinuclear MnIV4 complex shows 18 well-resolved hyperfine lines center around g=11 with an average hyperfine splitting of 36 G. This EPR spectrum is very similar to that found in the S1 state of the OEC. This is the first synthetic manganese model complex that shows an S1-like multiline spectrum in parallel-mode EPR

Mini-beam collimator enables microcrystallography experiments on standard beamlines

A ‘mini-beam’ apparatus has been developed that conditions the size of an X-ray beam to 5 µm. The design of the apparatus and the characterization of the focal size and flux are presented