The GANDER Microsatellite Radar Altimeter Constellation for Global Sea State Monitoring

In the last two decades satellite borne radar altimetry has been demonstrated as a very effective and accurate remote sensing method in sea state monitoring by over ten missions. Although all the previous missions have focused on oceanography, glaciology and land topography study, radar altimeter\u27s unique advantage in providing fast access altimetry measurement of significant wave height (SWH) and sea swface wind speed sensing has also generated great interests in several commercial applications such as a constellation for global real time sea safety monitoring and the shipping route management. In this paper, a low cost 12 microsatellite network called GANDER constellation (Global Altimeter Network Designed to Evaluate Risk), jointly proposed by Surrey Space Centre (SSC) and Satellite Observations System (SOS), is presented. The paper first gives an outline of the radar altimeter\u27s operational principle and main applications, then it focuses on a thorough feasibility analysis to demonstrate the microsatellite capability in this project, payload requirements as well as several most critical platform subsystems will be studied in detail. In the end, the 12 microsatellite constellations arrangement, which aims to provide world wide users of near real time access will be defined. This 12 small satellite system, as a much cheaper and more effective alternative for the conventional\u27 big\u27 multisensors spacecraft, will allow a much faster and more frequent update for the global sea state change monitoring. Its appearance well presents the small satellite research and application trend - cheaper by the dozens, andfaster by smaller

PACAP neuropeptide promotes Hepatocellular Protection via CREB-KLF4 dependent autophagy in mouse liver Ischemia Reperfusion Injury.

Organ ischemia reperfusion injury (IRI), associated with acute hepatocyte death, remains an unresolved problem in clinical orthotopic liver transplantation (OLT). Autophagy, an intracellular self-digesting progress, is responsible for cell reprograming required to regain post-stress homeostasis. Methods: Here, we analyzed the cytoprotective mechanism of pituitary adenylate cyclase-activating polypeptide (PACAP)-promoted hepatocellular autophagy in a clinically relevant mouse model of extended hepatic cold storage (4 °C UW solution for 20 h) followed by syngeneic OLT. Results: In contrast to 41.7% of liver graft failure by day 7 post-transplant in control group, PACAP treatment significantly improved graft survival (91.7% by day 14), and promoted autophagy-associated regeneration programs in OLT. In parallel in vitro studies, PACAP-enhanced autophagy ameliorated cellular damage (LDH/ALT levels), and diminished necrosis in H2O2-stressed primary hepatocytes. Interestingly, PACAP not only induced nuclear cAMP response element-binding protein (CREB), but also triggered reprogramming factor Kruppel-like factor 4 (KLF4) expression in IR-stressed OLT. Indeed, CREB inhibition attenuated hepatic autophagy and recreated hepatocellular injury in otherwise PACAP-protected livers. Furthermore, CREB inhibition suppressed PACAP-induced KLF4 expression, whereas KLF4 blockade abolished PACAP-promoted autophagy and neutralized PACAP-mediated hepatoprotection both in vivo and in vitro. Conclusion: Current study documents the essential neural regulation of PACAP-promoted autophagy in hepatocellular homeostasis in OLT, which provides the emerging therapeutic principle to combat hepatic IRI in OLT

Water oxidation with cobalt-loaded linear conjugated polymer photocatalysts

The first examples of linear conjugated organic polymer photocatalysts that produce oxygen from water after loading with cobalt and in the presence of an electron scavenger are reported. The oxygen evolution rates, which are higher than for related organic materials, can be rationalized by a combination of the thermodynamic driving force for water oxidation, the light absorption of the polymer, and the aqueous dispersibility of the relatively hydrophilic polymer particles. We also used transient absorption spectroscopy to study the best performing system and we found that fast oxidative quenching of the exciton occurs (picoseconds) in the presence of an electron scavenger, minimizing recombination

Edwardsiella Comparative Phylogenomics Reveal the New Intra/Inter-Species Taxonomic Relationships, Virulence Evolution and Niche Adaptation Mechanisms

Edwardsiella bacteria are leading fish pathogens causing huge losses to aquaculture industries worldwide. E. tarda is a broad-host range pathogen that infects more than 20 species of fish and other animals including humans while E. ictaluri is host-adapted to channel catfish causing enteric septicemia of catfish (ESC). Thus, these two species consist of a useful comparative system for studying the intricacies of pathogen evolution. Here we present for the first time the phylogenomic comparisons of 8 genomes of E. tarda and E. ictaluri isolates. Genome-based phylogenetic analysis revealed that E. tarda could be separate into two kinds of genotypes (genotype I, EdwGI and genotype II, EdwGII) based on the sequence similarity. E. tarda strains of EdwGI were clustered together with the E. ictaluri lineage and showed low sequence conservation to E. tarda strains of EdwGII. Multilocus sequence analysis (MLSA) of 48 distinct Edwardsiella strains also supports the new taxonomic relationship of the lineages. We identified the type III and VI secretion systems (T3SS and T6SS) as well as iron scavenging related genes that fulfilled the criteria of a key evolutionary factor likely facilitating the virulence evolution and adaptation to a broad range of hosts in EdwGI E. tarda. The surface structure-related genes may underlie the adaptive evolution of E. ictaluri in the host specification processes. Virulence and competition assays of the null mutants of the representative genes experimentally confirmed their contributive roles in the evolution/niche adaptive processes. We also reconstructed the hypothetical evolutionary pathway to highlight the virulence evolution and niche adaptation mechanisms of Edwardsiella. This study may facilitate the development of diagnostics, vaccines, and therapeutics for this under-studied pathogen

Genome Sequence of the Versatile Fish Pathogen Edwardsiella tarda Provides Insights into its Adaptation to Broad Host Ranges and Intracellular Niches

BACKGROUND:Edwardsiella tarda is the etiologic agent of edwardsiellosis, a devastating fish disease prevailing in worldwide aquaculture industries. Here we describe the complete genome of E. tarda, EIB202, a highly virulent and multi-drug resistant isolate in China. METHODOLOGY/PRINCIPAL FINDINGS:E. tarda EIB202 possesses a single chromosome of 3,760,463 base pairs containing 3,486 predicted protein coding sequences, 8 ribosomal rRNA operons, and 95 tRNA genes, and a 43,703 bp conjugative plasmid harboring multi-drug resistant determinants and encoding type IV A secretion system components. We identified a full spectrum of genetic properties related to its genome plasticity such as repeated sequences, insertion sequences, phage-like proteins, integrases, recombinases and genomic islands. In addition, analysis also indicated that a substantial proportion of the E. tarda genome might be devoted to the growth and survival under diverse conditions including intracellular niches, with a large number of aerobic or anaerobic respiration-associated proteins, signal transduction proteins as well as proteins involved in various stress adaptations. A pool of genes for secretion systems, pili formation, nonfimbrial adhesions, invasions and hemagglutinins, chondroitinases, hemolysins, iron scavenging systems as well as the incomplete flagellar biogenesis might feature its surface structures and pathogenesis in a fish body. CONCLUSION/SIGNIFICANCE:Genomic analysis of the bacterium offered insights into the phylogeny, metabolism, drug-resistance, stress adaptation, and virulence characteristics of this versatile pathogen, which constitutes an important first step in understanding the pathogenesis of E. tarda to facilitate construction of a practical effective vaccine used for combating fish edwardsiellosis

Microsatellite radar altimeter payload design for global sea state monitoring.

A detailed understanding of the relationship between altimetry measurement, especially significant wave height (SWH) measurement, and phase distortion is still unclear. Therefore, the objective of this Ph.D. study is first to outline this relationship by a simulation using a model that considers the errors from both the signal source and the power amplifier. The simulation results show the power amplifier influence is more significant than that of signal source in SWH estimation, and that the phase errors influence is worse for lower SWH conditions. It is recommended from the simulation that the group delay error of the whole transmitter link, after the chirp generator, should be well controlled to be under 0.5ns. In the payload design, Class-F is chosen as the amplifier operation mode due to its high efficiency and fewer harmonic frequency components. The difference between the operational principles of second and third harmonic peaking Class-F amplifiers have been illustrated by the simulation. Both of them can achieve high efficiency and high gain, however the third harmonic peaking Class-F is simpler to implement. Therefore it was chosen by the final design. In the simulation, a large signal STATZ model is set up, followed by the S-band Class-F amplifier design simulation and the implementation of third harmonic peaking Class-F amplifier. Based on this, an adaptive feedback group delay equalizer is proposed as a solution for the phase error compensation within the whole chirp signal swept bandwidth. A very simple but effective phase error detection and calculation circuit is designed, built and measured. The test branch results are very satisfying. Its small size and lower power consumption makes it very suitable for a compact microsatellite environment. In summary, the possibility of a medium resolution microsatellite borne radar altimeter for optimising shipping routes is investigated in this study. A 12 satellites constellation is proposed for achieving near real time altimetry broadcasting. The key payload design problems are identified in a thorough feasibility study: the restriction corresponding to these main problems is quantified via the SWH estimation simulation. A feedback linearization method is proposed as a promising solution for the compact microsatellite design with high power efficiency requirements, demonstrated by both simulation and hardware implementation results. (Abstract shortened by ProQuest.)

Zearalenone Degradation by Dielectric Barrier Discharge Cold Plasma: The Kinetics and Mechanism

In this study, dielectric barrier discharge (DBD) cold plasma was used to degrade zearalenone and the efficiency of degradation were evaluated. In addition, the degradation kinetics and possible pathway of degradation were investigated. The results showed that zearalenone degradation percentage increased with increasing voltage and time. When it was treated at 50 KV for 120 s, the degradation percentage could reach 98.28%. Kinetics analysis showed that the degradation process followed a first-order reaction, which fitted the exponential function model best (R² = 0.987). Meanwhile, liquid chromatographywith quadrupole time-of-flight mass spectrometry (Q-TOF LC/MS) was used to analyze the degradation products, one major compound was identified. In this study, the reactive species generated in cold plasma was analyzed by Optical Emission Spectroscopy (OES) and the free radicals were detected by Electron Spin Resonance (ESR). This study could provide a theoretical basis for the degradation of zearalenone to a certain extent