7,791 research outputs found
Continuous phase amplification with a Sagnac interferometer
We describe a weak value inspired phase amplification technique in a Sagnac
interferometer. We monitor the relative phase between two paths of a slightly
misaligned interferometer by measuring the average position of a split-Gaussian
mode in the dark port. Although we monitor only the dark port, we show that the
signal varies linearly with phase and that we can obtain similar sensitivity to
balanced homodyne detection. We derive the source of the amplification both
with classical wave optics and as an inverse weak value.Comment: 5 pages, 4 figures, previously submitted for publicatio
Saline nasal irrigation for acute upper respiratory tract infections (Review)
BACKGROUND: Acute upper respiratory tract infections (URTIs), including the common cold and rhinosinusitis, are common afflictions that cause discomfort and debilitation and contribute significantly to workplace absenteeism. Treatment is generally by antipyretic and decongestant drugs and sometimes antibiotics, even though most infections are viral. Nasal irrigation with saline is often employed as an adjunct treatment for URTI symptoms despite a relative lack of evidence for benefit in this clinical setting. This review is an update of the Cochrane review by Kassel et al, which found that saline was probably effective in reducing the severity of some symptoms associated with acute URTIs
Methylation-Sensitive Expression of a DNA Demethylase Gene Serves As an Epigenetic Rheostat
Genomes must balance active suppression of transposable elements (TEs) with the need to maintain gene expression. In Arabidopsis, euchromatic TEs are targeted by RNA-directed DNA methylation (RdDM). Conversely, active DNA demethylation prevents accumulation of methylation at genes proximal to these TEs. It is unknown how a cellular balance between methylation and demethylation activities is achieved. Here we show that both RdDM and DNA demethylation are highly active at a TE proximal to the major DNA demethylase gene ROS1. Unexpectedly, and in contrast to most other genomic targets, expression of ROS1 is promoted by DNA methylation and antagonized by DNA demethylation. We demonstrate that inducing methylation in the ROS1 proximal region is sufficient to restore ROS1 expression in an RdDM mutant. Additionally, methylation-sensitive expression of ROS1 is conserved in other species, suggesting it is adaptive. We propose that the ROS1 locus functions as an epigenetic rheostat, tuning the level of demethylase activity in response to methylation alterations, thus ensuring epigenomic stability.Pew Charitable Trusts (Biomedical Scholars Award)Alexander and Margaret Stewart Trust (Scholars Award
Statistical Analysis of Airport Network of China
Through the study of airport network of China (ANC), composed of 128 airports
(nodes) and 1165 flights (edges), we show the topological structure of ANC
conveys two characteristics of small worlds, a short average path length
(2.067) and a high degree of clustering (0.733). The cumulative degree
distributions of both directed and undirected ANC obey two-regime power laws
with different exponents, i.e., the so-called Double Pareto Law. In-degrees and
out-degrees of each airport have positive correlations, whereas the undirected
degrees of adjacent airports have significant linear anticorrelations. It is
demonstrated both weekly and daily cumulative distributions of flight weights
(frequencies) of ANC have power-law tails. Besides, the weight of any given
flight is proportional to the degrees of both airports at the two ends of that
flight. It is also shown the diameter of each sub-cluster (consisting of an
airport and all those airports to which it is linked) is inversely proportional
to its density of connectivity. Efficiency of ANC and of its sub-clusters are
measured through a simple definition. In terms of that, the efficiency of ANC's
sub-clusters increases as the density of connectivity does. ANC is found to
have an efficiency of 0.484.Comment: 6 Pages, 5 figure
Atom loss from Bose-Einstein condensates due to Feshbach resonance
In recent experiments on Na Bose-Einstein condensates [S. Inouye et al,
Nature 392, 151 (1998); J. Stenger et al, Phys. Rev. Lett. 82, 2422 (1999)],
large loss rates were observed when a time-varying magnetic field was used to
tune a molecular Feshbach resonance state near the state of pairs of atoms
belonging to the condensate many-body wavefunction. A mechanism is offered here
to account for the observed losses, based on the deactivation of the resonant
molecular state by interaction with a third condensate atom.Comment: LaTeX, 4 pages, 4 PostScript figures, uses REVTeX and psfig,
submitted to Physical Review A, Rapid Communication
Using Semantic Similarity and Text Embedding to Measure the Social Media Echo of Strategic Communications
Online discourse covers a wide range of topics and many actors tailor their
content to impact online discussions through carefully crafted messages and
targeted campaigns. Yet the scale and diversity of online media content make it
difficult to evaluate the impact of a particular message. In this paper, we
present a new technique that leverages semantic similarity to quantify the
change in the discussion after a particular message has been published. We use
a set of press releases from environmental organisations and tweets from the
climate change debate to show that our novel approach reveals a heavy-tailed
distribution of response in online discourse to strategic communications.Comment: 12 pages, 5 figure
Continuous Phase Amplification with a Sagnac Interferometer
We describe a phase-amplification technique using a Sagnac interferometer. We monitor the relative phase between two paths of a precisely misaligned interferometer by measuring the average position of a split-Gaussian mode in the dark port. Although we monitor only the dark port, we show that the signal varies linearly with phase and that we can obtain similar sensitivity to balanced homodyne detection. We derive the source of the amplification using classical wave optics
A LOFAR mini-survey for low-frequency radio emission from the nearest brown dwarfs
We have conducted a mini-survey for low-frequency radio emission from some of the closest brown dwarfs to the Sun with rapid rotation rates: SIMP J013656.5 +093347, WISEPC 150649.97+702736.0, and WISEPA J174124.26+255319.5.We have placed robust 3s upper limits on the flux density in the 111 – 169 MHz frequency range for these targets: WISE 1506: < 0:72 mJy; WISE 1741: < 0:87 mJy; SIMP 0136: < 0:66 mJy. At 8 hours of integration per target to achieve these limits, we find that systematic and detailed study of this class of object at LOFAR frequencies will require a substantial dedication of resources
An Untranslated cis-Element Regulates the Accumulation of Multiple C4 Enzymes in Gynandropsis gynandra Mesophyll Cells.
C4 photosynthesis is a complex phenotype that allows more efficient carbon capture than the ancestral C3 pathway. In leaves of C4 species, hundreds of transcripts increase in abundance compared with C3 relatives and become restricted to mesophyll (M) or bundle sheath (BS) cells. However, no mechanism has been reported that regulates the compartmentation of multiple enzymes in M or BS cells. We examined mechanisms regulating CARBONIC ANHYDRASE4 (CA4) in C4 Gynandropsis gynandra. Increased abundance is directed by both the promoter region and introns of the G. gynandra gene. A nine-nucleotide motif located in the 5' untranslated region (UTR) is required for preferential accumulation of GUS in M cells. This element is present and functional in three additional 5' UTRs and six 3' UTRs where it determines accumulation of two isoforms of CA and pyruvate,orthophosphate dikinase in M cells. Although the GgCA4 5' UTR is sufficient to direct GUS accumulation in M cells, transcripts encoding GUS are abundant in both M and BS. Mutating the GgCA4 5' UTR abolishes enrichment of protein in M cells without affecting transcript abundance. The work identifies a mechanism that directs cell-preferential accumulation of multiple enzymes required for C4 photosynthesis.We would like to thank the BBSRC for funding.This is the author accepted manuscript. The final version is available from the American Society of Plant Biologists via http://dx.doi.org/10.​1105/​tpc.​15.​0057
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