353 research outputs found
A genetic study on the activiation of quiescent Uq transposable elements in Zea mays L.
The standard a-ruq allele reports the activity of the Uq transposable element in the form of color spots or sectors of color spots in otherwise colorless aleurone tissue. As reported by this a-ruq, genomes of four maize inbred lines (C123, C103, B70 and 187-2) lack an active Uq element. However, these genomes contain quiescent Uq sequences that randomly and infrequently become activated;Spontaneous activation of quiescent Uq sequences during development of a-ruq/a-ruq/a-ruq endosperm results in sectors of Uq-a-ruq spotting in otherwise colorless aleurone tissue;Spontaneous germinal activation (at a rate of about 2 x 10[superscript]-4) of quiescent Uq sequences produces individual fully-spotted exceptional kernels of a-ruq/a-ruq/a-ruq genotype. Their spotting patterns differ from the pattern of the standard Uql-a-ruq spotting. Five new Uq elements, designated Uq2, Uq3, Uq4, Uq5, and Uq6, respectively, have been isolated. The genetic authenticity of these new Uq elements has been established;These five new Uq elements are independent of Uq1 and are clustered on one linkage group. Uq2 is allelic to Uq4, Uq3 is allelic to Uq5, whereas Uq6 is linked to both allelic pairs;Another quiescent Uq element has been activated in a maize plant upon treatment with 5-aza-2[superscript]\u27-deoxycytidine. This Uq consegregates with a coinduced miniature mutant that is found to be independent of mn1, mn2, and mn7690. The cosegregating genetic unit, designated Mn::Uq, acts dominantly and is not male transmissable. An in vitro pollen germination study shows that Mn::Uq pollen does not germinate, thereby causing this male nontransmissibility. Definitive genetic proof for the Uq nature of the mutant is given by the fact that a reconstitution testcross between a°/a°, Mn::Uq/+ and the a-ruq/a-ruq tester produces 50% spotted miniature and 50% colorless normal progeny;The Mn::Uq mutant does not transactivate the c-ruq65 and c-ruq67 alleles, two other Uq1-responding reporter alleles. In addition, Ug3, Ug4, and Ug5 transactivate the c-ruq alleles in a much weaker fashion than they transactivate a-ruq. These results suggest that structural differences may exist between these ruq receptor elements at the a-ruq and c-ruq alleles
Sendai Virus P Protein Is Constitutively Phosphorylated at Serine249: High Phosphorylation Potential of the P Protein
AbstractPreviously we showed that the Sendai virus P protein (568 aa) in virus-infected cells and in virions was primarily and constitutively phosphorylated on serine(s) in a single tryptic phosphopeptide TP1. By two-dimensional thin-layer electrophoresis and chromatography analysis of tryptic phosphopeptides of several deletion and point mutants of the P protein, we now show that the sole phosphorylation site in TP1 is serine249. Interestingly, when serine249 was deleted or mutagenized alternate potential serine sites were more heavily phosphorylated. A similar effect was observed when the deletion was very close to serine249 (Δ208–236). Mutagenesis of proline250 to alanine abrogated phosphorylation at serine249 suggesting that proline250 is essential for the primary phosphorylation of the P protein. Conceivably, serine249 phosphorylation is mediated by a proline-directed protein kinase. This finding is unusual because a majority of the P proteins from other negative-strand RNA viruses have been shown to be phosphorylated primarily by casein kinase II. Our results demonstrate that the P protein has a strong potency to remain phosphorylated. Based on our previous and present results, we suggest that the phosphorylation sites on P are dependent on the accessibility of phosphatases rather than kinases as all potential sites are about equally competent for phosphorylation. We propose that phosphorylation is important for maintaining the structural integrity of the Sendai virus P protein
Generation of Narrow-Band Polarization-Entangled Photon Pairs for Atomic Quantum Memories
We report an experimental realization of a narrow-band polarization-entangled
photon source with a linewidth of 9.6 MHz through cavity-enhanced spontaneous
parametric down-conversion. This linewidth is comparable to the typical
linewidth of atomic ensemble based quantum memories. Single-mode output is
realized by setting a reasonable cavity length difference between different
polarizations, using of temperature controlled etalons and actively stabilizing
the cavity. The entangled property is characterized with quantum state
tomography, giving a fidelity of 94% between our state and a maximally
entangled state. The coherence length is directly measured to be 32 m through
two-photon interference.Comment: 4 pages, 4 figure
Association between TGFBR1*6A and osteosarcoma: A Chinese case-control study
<p>Abstract</p> <p>Background</p> <p>TGFBR1*6A is a common hypomorphic variant of transforming growth factor β receptor 1 (TGFBR1). TGFBR1*6A is associated with an increased cancer risk, but the association of this polymorphism with osteosarcoma remains unknown. We have measured the frequency of TGFBR1*6A variants in osteosarcoma cases and controls.</p> <p>Methods</p> <p>Our case-control study is based on 168 osteosarcoma patients and 168 age- and gender-matched controls. Blood samples were obtained and the TGFBR1*6A variant determined by PCR amplification and DNA sequencing. The odds ratio (OR) and 95% confidence interval (95% CI) for the TGFBR1*6A polymorphism were calculated by unconditional logistic regression, adjusted for both age and gender. Three models - dominant, additive and recessive - were used to analyze the contribution of the TGFBR1*6A variant to osteosarcoma susceptibility.</p> <p>Results</p> <p>Heterozygotic and homozygotic TGFBR1*6A variants represented 50.4% and 6.0% of the 168 cases, whereas the controls had 18. 5% and 1.3%, respectively. ORs for homozygosity and heterozygosity of the TGFBR1*6A allele were 4.6 [95% CI, 2.33-7.97] and 2.9 [95% CI, 1.59-5.34] in the additive model. There were significant increases in the TGFBR1*6A variants in osteosarcoma cases compared to control in all 3 models. Further analysis showed that TGFBR1*6A genotypes were not associated with gender, age, or tumor location. However, TGFBR1*6A was significantly associated with less metastasis.</p> <p>Conclusions</p> <p>TGFBR1*6A, a dominant polymorphism of TGFBR1, is associated with increased susceptibility and metastasis spread of osteosarcoma.</p
Time-resolved boson sampling with photons of different colors
Interference of multiple photons via a linear-optical network has profound
applications for quantum foundation, quantum metrology and quantum computation.
Particularly, a boson sampling experiment with a moderate number of photons
becomes intractable even for the most powerful classical computers, and will
lead to "quantum supremacy". Scaling up from small-scale experiments requires
highly indistinguishable single photons, which may be prohibited for many
physical systems. Here we experimentally demonstrate a time-resolved version of
boson sampling by using photons not overlapping in their frequency spectra from
three atomic-ensemble quantum memories. Time-resolved measurement enables us to
observe nonclassical multiphoton correlation landscapes. An average fidelity
over several interferometer configurations is measured to be 0.936(13), which
is mainly limited by high-order events. Symmetries in the landscapes are
identified to reflect symmetries of the optical network. Our work thus provides
a route towards quantum supremacy with distinguishable photons.Comment: 5 pages, 3 figures, 1 tabl
Sequential generation of multiphoton entanglement with a Rydberg superatom
Multiqubit entanglement is an indispensable resource for quantum information
science. In particular, the entanglement of photons is of conceptual interest
due to its implications in measurement-based quantum computing, communication,
and metrology. The traditional way of spontaneous parametric down-conversion
already demonstrates entanglement of up to a dozen photons but is hindered by
its probabilistic nature. Here, we experimentally demonstrate an efficient
approach for multi-photon generation with a Rydberg superatom, a mesoscopic
atomic ensemble under Rydberg blockade. Using it as an efficient single-photon
interface, we iterate the photon creation process that gives rise to a train of
temporal photonic modes entangled in photon number degree. We detect the
multiphoton entanglement via converting the photon number degree to a time-bin
degree. Photon correlations verify entanglement up to 12 modes. The efficiency
scaling factor for adding one photon is 0.27, surpassing previous results, and
can be increased significantly without fundamental limitations.Comment: 11 pages, 9 figure
Experimental Free-Space Distribution of Entangled Photon Pairs over a Noisy Ground Atmosphere of 13km
We report free-space distribution of entangled photon pairs over a noisy
ground atmosphere of 13km. It is shown that the desired entanglement can still
survive after the two entangled photons have passed through the noisy ground
atmosphere. This is confirmed by observing a space-like separated violation of
Bell inequality of . On this basis, we exploit the distributed
entangled photon source to demonstrate the BB84 quantum cryptography scheme.
The distribution distance of entangled photon pairs achieved in the experiment
is for the first time well beyond the effective thickness of the aerosphere,
hence presenting a significant step towards satellite-based global quantum
communication.Comment: 4 pages, 3 figure
A Multicenter Randomized Controlled Trial of Malignant Gastric Outlet Obstruction: Tailored Partially Covered Stents (Placed Fluoroscopically) versus Standard Uncovered Stents (Placed Endoscopically)
The aim of our study is to compare the efficacy and safety of “outlet-shape” tailored stents with standard stents for the management of distal gastric cancer causing gastric outlet obstructions (GOOs) with varying gastric cavity shapes and sizes. To determine the shape and size of the GOOs, stomach opacifications were performed using contrast media before stenting. Two basic shapes of the residual cavity of the proximal GOO were observed: cup shaped or approximately cup shaped and funnel shaped or approximately funnel shaped. Other shapes were not found. In the GOO tailored group, the size and shape of the proximal ends of the tailored stent were suited for the residual cavity of the proximal GOO. The tailored stents included large cup-shaped stents and large funnel-shaped stents. GOO tailored covered stents led to less restenosis and reintervention rates compared to standard uncovered stents but with the same survival
2-(4-Chlorophenyl)-5-(3,4-dimethoxyphenethyl)-6,7-dihydropyrazolo[1,5-a]pyrazin-4(5H)-one
In the title compound, C22H22ClN3O3, the dihedral angles between the planes of the benzene rings and the pyrazole ring are 16.05 (10) and 84.84 (10)°. The conformation of the six-membered heterocyclic ring is close to a screw-boat. The crystal packing is stabilized by weak intermolecular C—H⋯O interactions and is also consolidated by C—H⋯π interactions
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