1,701 research outputs found
Constructing Infinitary Quotient-Inductive Types
This paper introduces an expressive class of quotient-inductive types, called
QW-types. We show that in dependent type theory with uniqueness of identity
proofs, even the infinitary case of QW-types can be encoded using the
combination of inductive-inductive definitions involving strictly positive
occurrences of Hofmann-style quotient types, and Abel's size types. The latter,
which provide a convenient constructive abstraction of what classically would
be accomplished with transfinite ordinals, are used to prove termination of the
recursive definitions of the elimination and computation properties of our
encoding of QW-types. The development is formalized using the Agda theorem
prover
Synthesis of Fe2O3 Nanoparticles and their Catalytic Activity for the Reduction of Halonitroarenes under Sustainable Conditions
Fe2O3 nanoparticles (NPs) with mean size of 50 nm ca. are synthesized starting from a porous organic polymer containing beta-ketoesterate Fe(III) sites (Fe-POP), which is annealed at 400 degrees C under air for 30 min. During calcination, the organic material partially decomposes, and iron(III) oxide NPs onto an organic residue could be observed after annealing. The obtained NPs are characterized by SEM-EDS, IR, and magnetic analyses and they are employed as active catalysts in the reduction of p-bromonitrobenzene into p-bromoaniline, using hydrazine hydrate in ethano
18S rDNA Phylogeny of Lamproderma and Allied Genera (Stemonitales, Myxomycetes, Amoebozoa)
The phylogenetic position of the slime-mould genus Lamproderma (Myxomycetes, Amoebozoa) challenges traditional taxonomy: although it displays the typical characters of the order Stemonitales, it appears to be sister to Physarales. This study provides a small subunit (18S or SSU) ribosomal RNA gene-based phylogeny of Lamproderma and its allies, with new sequences from 49 specimens in 12 genera. We found that the order Stemonitales and Lamproderma were both ancestral to Physarales and that Lamproderma constitutes several clades intermingled with species of Diacheopsis, Colloderma and Elaeomyxa. We suggest that these genera may have evolved from Lamproderma by multiple losses of fruiting body stalks and that many taxonomic revisions are needed. We found such high genetic diversity within three Lamproderma species that they probably consist of clusters of sibling species. We discuss the contrasts between genetic and morphological divergence and implications for the morphospecies concept, highlighting the phylogenetically most reliable morphological characters and pointing to others that have been overestimated. In addition, we showed that the first part (∼600 bases) of the SSU rDNA gene is a valuable tool for phylogeny in Myxomycetes, since it displayed sufficient variability to distinguish closely related taxa and never failed to cluster together specimens considered of the same species
Ultrafast nonlocal control of spontaneous emission
Solid-state cavity quantum electrodynamics systems will form scalable nodes
of future quantum networks, allowing the storage, processing and retrieval of
quantum bits, where a real-time control of the radiative interaction in the
cavity is required to achieve high efficiency. We demonstrate here the dynamic
molding of the vacuum field in a coupled-cavity system to achieve the ultrafast
nonlocal modulation of spontaneous emission of quantum dots in photonic crystal
cavities, on a timescale of ~200 ps, much faster than their natural radiative
lifetimes. This opens the way to the ultrafast control of semiconductor-based
cavity quantum electrodynamics systems for application in quantum interfaces
and to a new class of ultrafast lasers based on nano-photonic cavities.Comment: 15 pages, 4 figure
Cloud impacts on photochemistry: Building a climatology of photolysis rates from the Atmospheric Tomography mission
Abstract. Measurements from actinic flux spectroradiometers on board the
NASA DC-8 during the Atmospheric Tomography (ATom) mission provide an
extensive set of statistics on how clouds alter photolysis rates (J values)
throughout the remote Pacific and Atlantic Ocean basins. J values control
tropospheric ozone and methane abundances, and thus clouds have been included
for more than three decades in tropospheric chemistry modeling. ATom made
four profiling circumnavigations of the troposphere capturing each of the
seasons during 2016–2018. This work examines J values from the Pacific
Ocean flights of the first deployment, but publishes the complete Atom-1 data
set (29 July to 23 August 2016). We compare the observed J values (every 3 s along flight track) with those calculated by nine global
chemistry–climate/transport models (globally gridded, hourly, for a
mid-August day). To compare these disparate data sets, we build a
commensurate statistical picture of the impact of clouds on J values using
the ratio of J-cloudy (standard, sometimes cloudy conditions) to J-clear
(artificially cleared of clouds). The range of modeled cloud effects is
inconsistently large but they fall into two distinct classes: (1)Â models with
large cloud effects showing mostly enhanced J values aloft and or
diminished at the surface and (2)Â models with small effects having nearly
clear-sky J values much of the time. The ATom-1 measurements generally
favor large cloud effects but are not precise or robust enough to point out
the best cloud-modeling approach. The models here have resolutions of 50–200 km
and thus reduce the occurrence of clear sky when averaging over grid
cells. In situ measurements also average scattered sunlight over a mixed
cloud field, but only out to scales of tens of kilometers. A primary uncertainty
remains in the role of clouds in chemistry, in particular, how models average
over cloud fields, and how such averages can simulate measurements.
NERC ACSIS LTSM projec
Use of Intravenous Peramivir for Treatment of Severe Influenza A(H1N1)pdm09
Oral antiviral agents to treat influenza are challenging to administer in the intensive care unit (ICU). We describe 57 critically ill patients treated with the investigational intravenous neuraminidase inhibitor drug peramivir for influenza A (H1N1)pdm09 [pH1N1]. Most received late peramivir treatment following clinical deterioration in the ICU on enterically-administered oseltamivir therapy. The median age was 40 years (range 5 months-81 years). Common clinical complications included pneumonia or acute respiratory distress syndrome requiring mechanical ventilation (54; 95%), sepsis requiring vasopressor support (34/53; 64%), acute renal failure requiring hemodialysis (19/53; 36%) and secondary bacterial infection (14; 25%). Over half (29; 51%) died. When comparing the 57 peramivir-treated cases with 1627 critically ill cases who did not receive peramivir, peramivir recipients were more likely to be diagnosed with pneumonia/acute respiratory distress syndrome (p = 0.0002) or sepsis (p = <0.0001), require mechanical ventilation (p = <0.0001) or die (p = <0.0001). The high mortality could be due to the pre-existing clinical severity of cases prior to request for peramivir, but also raises questions about peramivir safety and effectiveness in hospitalized and critically ill patients. The use of peramivir merits further study in randomized controlled trials, or by use of methods such as propensity scoring and matching, to assess clinical effectiveness and safety
Genetic Structure of Two Protist Species (Myxogastria, Amoebozoa) Suggests Asexual Reproduction in Sexual Amoebae
Plasmodial slime molds (Myxogastria or Myxomycetes) are common and widespread unicellular organisms that are commonly assumed to have a sexual life cycle culminating with the formation of often macroscopic fruiting bodies that efficiently disseminate spores. However, laboratory studies based on mating compatibility revealed the coexistence of asexual as well as sexual strains. To test this hypothesis in natural populations, we investigated the genetic variability of two species of the genus Lamproderma. Detailed ecological relevés were carried out in 2007 and 2009 in several deep ravines in the Elbsandsteingebirge (Saxony, south-eastern Germany). Morphological characters of 93 specimens of Lamproderma were recorded and genetic analyses, based on the small subunit ribosomal gene, the internal transcribed spacer 1 and partial elongation factor 1α sequences were carried out for 52 specimens. Genetic analyses showed the existence of two major clades, each composed of several discrete lineages. Most of these lineages were composed of several identical sequences (SSU, ITS 1 and EF-1α) which is explained best by an asexual mode of reproduction. Detrended Correspondence Analysis of morphological characters revealed two morphospecies that corresponded to the two major clades, except for one genotype (Lc6), thus challenging the morphospecies concept. Genetic patterns were not related to the geographical distribution: specimens belonging to the same genotype were found in distinct ravines, suggesting effective long-distance dispersal via spores, except for the Lc6 genotype which was found only in one ravine. Implications for the morphological and biological species concept are discussed
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