790 research outputs found
Diversity and structure of soil bacterial communities in the Fildes Region (maritime Antarctica) as revealed by 454 pyrosequencing
This study assessed the diversity and composition of bacterial communities in four different soils (human-, penguin-, seal-colony impacted soils and pristine soil) in the Fildes Region (King George Island, Antarctica) using 454 pyrosequencing with bacterial-specific primers targeting the 16S rRNA gene. Proteobacteria, Actinobacteria, Acidobacteria, and Verrucomicrobia were abundant phyla in almost all the soil samples. The four types of soils were significantly different in geochemical properties and bacterial community structure. Thermotogae, Cyanobacteria, Fibrobacteres, Deinococcus-Thermus, and Chlorobi obviously varied in their abundance among the 4 soil types. Considering all the samples together, members of the genera Gaiella, Chloracidobacterium, Nitrospira, Polaromonas, Gemmatimonas, Sphingomonas and Chthoniobacter were found to predominate, whereas members of the genera Chamaesiphon, Herbaspirillum, Hirschia, Nevskia, Nitrosococcus, Rhodococcus, Rhodomicrobium, and Xanthomonas varied obviously in their abundance among the four soil types. Distance-based redundancy analysis revealed that pH (p < 0.01), phosphate phosphorus (p < 0.01), organic carbon (p < 0.05), and organic nitrogen (p < 0.05) were the most significant factors that correlated with the community distribution of soil bacteria. To our knowledge, this is the first study to explore the soil bacterial communities in human-, penguin-, and seal- colony impacted soils from ice-free areas in maritime Antarctica using high-throughput pyrosequencing
Extension of ELM suppression window using n=4 RMPs in EAST
The q95 window for Type-I Edge Localized Modes (ELMs) suppression using n=4
even parity Resonant Magnetic Perturbations (RMPs) has been significantly
expanded to a range from 3.9 to 4.8, which is demonstrated to be reliable and
repeatable in EAST over the last two years. This window is significantly wider
than the previous one, which is around q95=3.7pm0.1, and is achieved using n=4
odd parity RMPs. Here, n represents the toroidal mode number of the applied
RMPs and q95 is the safety factor at the 95% normalized poloidal magnetic flux.
During ELM suppression, there is only a slight drop in the stored energy
(<=10%). The comparison of pedestal density profiles suggests that ELM
suppression is achieved when the pedestal gradient is kept lower than a
threshold. This wide q95 window for ELM suppression is consistent with the
prediction made by MARS-F modeling prior to the experiment, in which it is
located at one of the resonant q95 windows for plasma response. The Chirikov
parameter taking into account plasma response near the pedestal top, which
measures the plasma edge stochasticity, significantly increases when q95
exceeds 4, mainly due to denser neighboring rational surfaces. Modeling of
plasma response by the MARS-F code shows a strong coupling between resonant and
non-resonant components across the pedestal region, which is characteristic of
the kink-peeling like response observed during RMP-ELM suppression in previous
studies on EAST. These promising results show the reliability of ELM
suppression using the n=4 RMPs and expand the physical understanding on ELM
suppression mechanism.Comment: 25 pages, 11 figure
Self-Assembled Thin-Layer Glycomaterials With a Proper Shell Thickness for Targeted and Activatable Cell Imaging
The construction of targeted and activatable materials can largely improve the precision of disease diagnosis and therapy. However, the currently developed systems either target a transmembrane antigen or are activatable to release imaging and/or therapeutic reagents intracellularly. Here, we develop a simple thin-layer glycomaterial through the self-assembly between fluorescent glycoprobes, in which the carbohydrate-targeting reagent and the fluorophore are linked to each other by polyethylene glycol with a suitable chain length, and thin-layer manganese dioxide. The fluorogenic material developed is both capable of targeting a transmembrane glycoprotein receptor and fluorescently activatable by intracellular biothiols. The shell thickness of the material was determined to be important for achieving the biothiol-induced activation of fluorescence. This research might provide insight into the development of precision-enhanced self-assembled materials for disease theranostics
Topological Photonics
Topology is revolutionizing photonics, bringing with it new theoretical
discoveries and a wealth of potential applications. This field was inspired by
the discovery of topological insulators, in which interfacial electrons
transport without dissipation even in the presence of impurities. Similarly,
new optical mirrors of different wave-vector space topologies have been
constructed to support new states of light propagating at their interfaces.
These novel waveguides allow light to flow around large imperfections without
back-reflection. The present review explains the underlying principles and
highlights the major findings in photonic crystals, coupled resonators,
metamaterials and quasicrystals.Comment: progress and review of an emerging field, 12 pages, 6 figures and 1
tabl
Direct Measurements of the Branching Fractions for and and Determinations of the Form Factors and
The absolute branching fractions for the decays and
are determined using singly
tagged sample from the data collected around 3.773 GeV with the
BES-II detector at the BEPC. In the system recoiling against the singly tagged
meson, events for and events for decays are observed. Those yield
the absolute branching fractions to be and . The
vector form factors are determined to be
and . The ratio of the two form
factors is measured to be .Comment: 6 pages, 5 figure
Search for the Lepton Flavor Violation Processes and
The lepton flavor violation processes and are
searched for using a sample of 5.8 events collected with
the BESII detector. Zero and one candidate events, consistent with the
estimated background, are observed in and
decays, respectively. Upper limits on the branching ratios are determined to be
and at the 90% confidence level (C.L.).Comment: 9 pages, 2 figure
The pole in
Using a sample of 58 million events recorded in the BESII detector,
the decay is studied. There are conspicuous
and signals. At low mass, a large
broad peak due to the is observed, and its pole position is determined
to be - MeV from the mean of six analyses.
The errors are dominated by the systematic errors.Comment: 15 pages, 6 figures, submitted to PL
Observation of the decay \psip\rar\kstark
Using 14 million events collected with the BESII detector,
branching fractions of \psip\rar\kstarkpm and \kstarknn are determined to
be: \calB(\psip\rar\kstarkpm)=(2.9^{+1.3}_{-1.7}\pm0.4)\times 10^{-5} and
\calB(\psip\rar\kstarknn)=(13.3^{+2.4}_{-2.7}\pm1.9)\times 10^{-5}. The
results confirm the violation of the "12%" rule for these two decay channels
with higher precision. A large isospin violation between the charged and
neutral modes is observed.Comment: 5 pages, 3 figure
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