How Fast is Your Detector? The Effect of Temporal Response on Image Quality

With increasing interest in high-speed imaging should come an increased interest in the response times of our scanning transmission electron microscope (STEM) detectors. Previous works have previously highlighted and contrasted performance of various detectors for quantitative compositional or structural studies, but here we shift the focus to detector temporal response, and the effect this has on captured images. The rise and decay times of eight detectors' single electron response are reported, as well as measurements of their flatness, roundness, smoothness, and ellipticity. We develop and apply a methodology for incorporating the temporal detector response into simulations, showing that a loss of resolution is apparent in both the images and their Fourier transforms. We conclude that the solid-state detector outperforms the photomultiplier-tube (PMT) based detectors in all areas bar a slightly less elliptical central hole and is likely the best detector to use for the majority of applications. However, using tools introduced here we encourage users to effectively evaluate what detector is most suitable for their experimental needs

Genome-wide transcriptional profiling of appressorium development by the rice blast fungus Magnaporthe oryzae.

addresses: College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.notes: PMCID: PMC3276559The rice blast fungus Magnaporthe oryzae is one of the most significant pathogens affecting global food security. To cause rice blast disease the fungus elaborates a specialised infection structure called an appressorium. Here, we report genome wide transcriptional profile analysis of appressorium development using next generation sequencing (NGS). We performed both RNA-Seq and High-Throughput SuperSAGE analysis to compare the utility of these procedures for identifying differential gene expression in M. oryzae. We then analysed global patterns of gene expression during appressorium development. We show evidence for large-scale gene expression changes, highlighting the role of autophagy, lipid metabolism and melanin biosynthesis in appressorium differentiation. We reveal the role of the Pmk1 MAP kinase as a key global regulator of appressorium-associated gene expression. We also provide evidence for differential expression of transporter-encoding gene families and specific high level expression of genes involved in quinate uptake and utilization, consistent with pathogen-mediated perturbation of host metabolism during plant infection. When considered together, these data provide a comprehensive high-resolution analysis of gene expression changes associated with cellular differentiation that will provide a key resource for understanding the biology of rice blast disease

Preparation and characterization of hydrogels with potential for use as biomaterials

Hydrogels have been extensively explored for biomedical applications due to their ability to absorb high water content in its structure, which gives excellent biocompatibility. This work aims at obtaining biocompatible hydrogels with potential for use in increasing the mechanical strength of bone substitutes, or controlled drug release. Poly (N-vinyl-2-pyrrolidone) hydrogels were prepared by free radical polymerization with and without the addition of acrylic acid. Azobisisobutyronitrile and ammonium persulfate were used as initiator and N,N-methylenebisacrylamide was used as the crosslinking agent. The characterization of the hydrogels was performed by thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy and swelling properties. The results obtained demonstrate different degrees of crosslinking and swelling of up to 490 ± 30%. The different properties of the hydrogels suggest different applications

Eddy covariance measurements of the sea spray aerosol flux over the open ocean

Direct eddy covariance measurements of size-segregated sea spray aerosol fluxes over the open Atlantic Ocean are presented, along with a source function derived from them for a wind speed range of 4 to 18 m s -1 and a size range of 0.176 < R 80 < 6.61 μm. This is in broad agreement with other recent estimates of the source function over this size range but shows a more rapid decrease with size above R 80 = 2 μm than most other functions. The measurements were made during a 3 week cruise in the North Atlantic as part of the UK contribution to the international Surface Ocean-Lower Atmosphere Study (SOLAS) program. They utilized the new high-rate Compact Lightweight Aerosol Spectrometer Probe (CLASP), providing a 16-channel size spectrum (0.17 < R amb < 9.5 μm) at 10 Hz, collocated with a sonic anemometer. The measurements demonstrate the high variability in sea spray aerosol flux compared with other air-sea fluxes, both between individual estimates and in the scales contributing to the flux