POES satellite observations of EMIC-wave driven relativistic electron precipitation during 1998-2010

[1] Using six Polar Orbiting Environmental Satellites (POES) satellites that have carried the Space Environment Module-2 instrument package, a total of 436,422 individual half-orbits between 1998 and 2010 were inspected by an automatic detection algorithm searching for electromagnetic ion cyclotron (EMIC) driven relativistic electron precipitation (REP). The algorithm searched for one of the key characteristics of EMIC-driven REP, identified as the simultaneity between spikes in the P1 (52 keV differential proton flux channel) and P6 (>800 keV electron channel). In all, 2331 proton precipitation associated REP (PPAREP) events were identified. The majority of events were observed at L-values within the outer radiation belt (3 < L < 7) and were more common in the dusk and night sectors as determined by magnetic local time. The majority of events occurred outside the plasmasphere, at L-values ~1 Re greater than the plasmapause location determined from two different statistical models. The events make up a subset of EMIC-driven proton spikes investigated by Sandanger et al. (2009), and potentially reflect different overall characteristics compared with proton spikes, particularly when comparing their location to that of the plasmapause, i.e., EMIC-driven proton precipitation inside the plasmapause, and potentially EMIC-driven REP outside the plasmapause. There was no clear relationship between the location of plasmaspheric plumes and the locations of the PPAREP events detected. Analysis of the PPAREP event occurrence indicates that high solar wind speed and high geomagnetic activity levels increase the likelihood of an event being detected. The peak PPAREP event occurrence was during the declining phase of solar cycle 23, consistent with the 2003 maximum in the geomagnetic activity index, Ap

Very low latitude whistler‐mode signals: Observations at three widely spaced latitudes

VLF radio signals with travel times ~100 ms were observed continuously for up to ~11 hours at night on Rarotonga (Cook Islands, ~21°S) at 21.4 kHz from US Navy transmitter NPM, Hawaii (~21°N). These signals travelled in the whistler‐mode on well‐defined paths, though not field‐aligned ducts, through the ionospheric F region, and across the equator reaching altitudes ~700‐1400 km depending on time of night. These same signals were also observed simultaneously in Dunedin (46°S), New Zealand, with very nearly the same travel times but with somewhat lower amplitudes and occurrence rates, consistent with the whistler‐mode part of the propagation being at very low latitudes. Both sets of signals had similar Doppler shifts, typically tens of mHz, but sometimes up to a few hundred mHz, being positive during most of the night, while the whistler‐mode group delays decreased due to both the shortening of the path and the decay of the near equatorial ionosphere, but negative near dawn when the Sun's rays start ionizing the F region. The signals are not observable during the day, fading out during dawn, due to increasing attenuation from the increasing electron density, and hence increasing collisions, in both the D and F regions. Similar weaker NPM signals were also seen at Rothera (68°S). In addition, similar 24.8 kHz signals were seen from the more distant NLK (Seattle, ~48°N) at Rarotonga, though clearly weaker than from NPM, but not at Dunedin

A Microcomputer-Based Data Acquisition System with Hardware Capabilities to Calculate a Fast Fourier Transform

The Fast Fourier Transform (FFT) Has in Recent Years Become an Important Tool to the Engineer. There Are a Number of Algorithms Which Calculate the FFT. One Such Algorithm is the Cooley-Tukey FFT Algorithm (Radix-2) Which Lends itself Rather Easily to a Combination Software and Hardware Implementation. with a Microcomputer as the Controller of a Data Acquisition Module and Hardware Which Computes the Butterfly Associated with the FFT Algorithm, the FFT Can Be Calculated Efficiently. © 1979 IEE

Engineering soil organic matter quality: Biodiesel Co-Product (BCP) stimulates exudation of nitrogenous microbial biopolymers

Biodiesel Co-Product (BCP) is a complex organic material formed during the transesterification of lipids. We investigated the effect of BCP on the extracellular microbial matrix or ‘extracellular polymeric substance’ (EPS) in soil which is suspected to be a highly influential fraction of soil organic matter (SOM). It was hypothesised that more N would be transferred to EPS in soil given BCP compared to soil given glycerol. An arable soil was amended with BCP produced from either 1) waste vegetable oils or 2) pure oilseed rape oil, and compared with soil amended with 99% pure glycerol; all were provided with 15N labelled KNO3. We compared transfer of microbially assimilated 15N into the extracellular amino acid pool, and measured concomitant production of exopolysaccharide. Following incubation, the 15N enrichment of total hydrolysable amino acids (THAAs) indicated that intracellular anabolic products had incorporated the labelled N primarily as glutamine and glutamate. A greater proportion of the amino acids in EPS were found to contain 15N than those in the THAA pool, indicating that the increase in EPS was comprised of bioproducts synthesised de novo. Moreover, BCP had increased the EPS production efficiency of the soil microbial community (μg EPS per unit ATP) up to approximately double that of glycerol, and caused transfer of 21% more 15N from soil solution into EPS-amino acids. Given the suspected value of EPS in agricultural soils, the use of BCP to stimulate exudation is an interesting tool to consider in the theme of delivering sustainable intensification

The Effect of Oligomerization on A Solid-Binding Peptide Binding to Silica-Based Materials.

The bifunctional linker-protein G (LPG) fusion protein comprises a peptide (linker) sequence and a truncated form of Streptococcus strain G148 protein G (protein G). The linker represents a multimeric solid-binding peptide (SBP) comprising 4 × 21-amino acid sequence repeats that display high binding affinity towards silica-based materials. In this study, several truncated derivatives were investigated to determine the effect of the SBP oligomerization on the silica binding function of LPG (for the sake of clarity, LPG will be referred from here on as 4 × LPG). Various biophysical characterization techniques were used to quantify and compare the truncated derivatives against 4 × LPG and protein G without linker (PG). The derivative containing two sequence repeats (2 × LPG) showed minimal binding to silica, while the truncated derivative with only a single sequence (1 × LPG) displayed no binding. The derivative containing three sequence repeats (3 × LPG) was able to bind to silica with a binding affinity of KD = 53.23 ± 4.5 nM, which is 1.5 times lower than that obtained for 4 × LPG under similar experimental conditions. Circular dichroism (CD) spectroscopy and fluorescence spectroscopy studies indicated that the SBP degree of oligomerization has only a small effect on the secondary structure (the linker unravels the beginning of the protein G sequence) and chemical stability of the parent protein G. However, based on quartz crystal microbalance with dissipation monitoring (QCM-D), oligomerization is an important parameter for a strong and stable binding to silica. The replacement of three sequence repeats by a (GGGGS)12 glycine-rich spacer indicated that the overall length rather than the SBP oligomerization mediated the effective binding to silica

Diatom Proteomics Reveals Unique Acclimation Strategies to Mitigate Fe Limitation

Phytoplankton growth rates are limited by the supply of iron (Fe) in approximately one third of the open ocean, with major implications for carbon dioxide sequestration and carbon (C) biogeochemistry. To date, understanding how alteration of Fe supply changes phytoplankton physiology has focused on traditional metrics such as growth rate, elemental composition, and biophysical measurements such as photosynthetic competence (Fv/Fm). Researchers have subsequently employed transcriptomics to probe relationships between changes in Fe supply and phytoplankton physiology. Recently, studies have investigated longer-term (i.e. following acclimation) responses of phytoplankton to various Fe conditions. In the present study, the coastal diatom, Thalassiosira pseudonana, was acclimated (10 generations) to either low or high Fe conditions, i.e. Fe-limiting and Fe-replete. Quantitative proteomics and a newly developed proteomic profiling technique that identifies low abundance proteins were employed to examine the full complement of expressed proteins and consequently the metabolic pathways utilized by the diatom under the two Fe conditions. A total of 1850 proteins were confidently identified, nearly tripling previous identifications made from differential expression in diatoms. Given sufficient time to acclimate to Fe limitation, T. pseudonana up-regulates proteins involved in pathways associated with intracellular protein recycling, thereby decreasing dependence on extracellular nitrogen (N), C and Fe. The relative increase in the abundance of photorespiration and pentose phosphate pathway proteins reveal novel metabolic shifts, which create substrates that could support other well-established physiological responses, such as heavily silicified frustules observed for Fe-limited diatoms. Here, we discovered that proteins and hence pathways observed to be down-regulated in short-term Fe starvation studies are constitutively expressed when T. pseudonana is acclimated (i.e., nitrate and nitrite transporters, Photosystem II and Photosystem I complexes). Acclimation of the diatom to the desired Fe conditions and the comprehensive proteomic approach provides a more robust interpretation of this dynamic proteome than previous studies.This work was supported by National Science Foundation grants OCE1233014 (BLN) and the Office of Polar Programs Postdoctoral Fellowship grant 0444148 (BLN). DRG was supported by National Institutes of Health 5P30ES007033-10. AH and MTM were supported by Natural Sciences and Engineering Research Council of Canada. RFS and PWB were supported by the New Zealand Royal Society Marsden Fund and the Ministry of Science. This work is supported in part by the University of Washington's Proteomics Computer Resource Centre (UWPR95794). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Liver test abnormalities in patients with HIV mono-infection : assessment with simple non-invasive fibrosis markers

BACKGROUND: Patients with HIV mono-infection may develop chronic liver disease due to a number of factors including hepatic steatosis. We estimated the prevalence and predictors of hepatic steatosis and fibrosis in a cohort of HIV-mono-infected patients with persistently deranged liver function tests. METHODS: Of 2398 consecutive patients at one UK clinical center, 156 (6.5%) had persistently abnormal transaminases in at least two measurements six months apart. We used APRI and FIB4 scores to determine the presence of significant and/or advanced fibrosis in this group as well as its potential associations. RESULTS: Mean age was 47.5\ub18.5 years and 91% (142/156) were males. Diabetes mellitus was present in 11% of patients; hypertension in 18%; and dyslipidemia in 52%. Almost all were on antiretroviral therapy (ART) (97%) and most were virologically suppressed (94%). Steatosis was detected by ultrasound in 71% of patients. The prevalence of FIB4 641.45, 1.46-3.24 and &gt;3.25 was 67%, 29% and 4%, respectively, and that of APRI 640.5, 0.51-1.49 and &gt;1.5 was 52%, 45% and 3% respectively. In multivariate analysis, only cumulative ART exposure was associated with FIB4&gt;1.45 (odds ratio [OR] 1.008, 95% confidence interval [CI] 1.000-1.016), while APRI&gt;0.5 was associated with higher alanine aminotransferase levels (OR 1.033, 95%CI 1.015-1.510). Twenty patients had a liver biopsy, of whom 13 had non-alcoholic fatty liver disease (NAFLD). CONCLUSIONS: Elevated transaminases are often present in HIV-mono-infected patients and this may be associated with NAFLD and/or ART. Non-invasive screening for the presence of NAFLD and fibrosis in all HIV-mono-infected patients as part of their routine clinical management should be further explore

Lightning driven inner radiation belt energy deposition into the atmosphere: regional and global estimates

International audienceIn this study we examine energetic electron precipitation fluxes driven by lightning, in order to determine the global distribution of energy deposited into the middle atmosphere. Previous studies using lightning-driven precipitation burst rates have estimated losses from the inner radiation belts. In order to confirm the reliability of those rates and the validity of the conclusions drawn from those studies, we have analyzed New Zealand data to test our global understanding of troposphere to magnetosphere coupling. We examine about 10000h of AbsPAL recordings made from 17 April 2003 through to 26 June 2004, and analyze subionospheric very-low frequency (VLF) perturbations observed on transmissions from VLF transmitters in Hawaii (NPM) and western Australia (NWC). These observations are compared with those previously reported from the Antarctic Peninsula. The perturbation rates observed in the New Zealand data are consistent with those predicted from the global distribution of the lightning sources, once the different experimental configurations are taken into account. Using lightning current distributions rather than VLF perturbation observations we revise previous estimates of typical precipitation bursts at L~2.3 to a mean precipitation energy flux of ~1×10-3 ergs cm-2s-1. The precipitation of energetic electrons by these bursts in the range L=1.9-3.5 will lead to a mean rate of energy deposited into the atmosphere of 3×10-4 ergs cm-2min-1, spatially varying from a low of zero above some ocean regions to highs of ~3-6×10-3 ergs cm-2min-1 above North America and its conjugate region

The Effects of Grace Interventions in Church Communities

Grace remains little studied though several recent studies have developed promising ways to measure grace. Here we report two studies involving grace interventions as part of an ongoing investigation of positive psychology in the context of Christian church communities, Study One used a crossover design in which two congregations were measured on grace and other variables at the outset, and again after phases one and two. One congregation received a grace intervention during phase one and the second during phase two. Results showed increased scores on grace but not an expected increase in marital satisfaction among married participants. Study Two used a similar design with two additional congregations to assess effects of a grace intervention on selfforgiveness. As expected, congregants receiving the grace intervention showed increases in trait self-forgiveness when compared to those in the wait-list