378 research outputs found
Distinguishing between fake news and satire with transformers
Indiscriminate elimination of harmful fake news risks destroying satirical news, which can be benign or even beneficial, because both types of news share highly similar textual cues. In this work we applied a recent development in neural network architecture, transformers, to the task of separating satirical news from fake news. Transformers have hitherto not been applied to this specific problem. Our evaluation results on a publicly available and carefully curated dataset show that the performance from a classifier framework built around a DistilBERT architecture performed better than existing machine-learning approaches. Additional improvement over baseline DistilBERT was achieved through the use of non-standard tokenization schemes as well as varying the pre-training and text pre-processing strategies. The improvement over existing approaches stands at 0.0429 (5.2%) in F1 and 0.0522 (6.4%) in accuracy. Further evaluation on two additional datasets shows our framework\u27s ability to generalize across datasets without diminished performance
Ginseng and Ginkgo Biloba effects on cognition as modulated by cardiovascular reactivity: A randomised trial
Background
There is some evidence to suggest that ginseng and Ginkgo biloba can improve cognitive performance, however, very little is known about the mechanisms associated with such improvement. Here, we tested whether cardiovascular reactivity to a task is associated with cognitive improvement.
Methodology/Principal findings
Using a double-blind, placebo controlled, crossover design, participants (N = 24) received two doses of Panax Ginseng (500, 1000 mg) or Ginkgo Biloba (120, 240 mg) (N = 24), and underwent a series of cognitive tests while systolic, diastolic, and heart rate readings were taken. Ginkgo Biloba improved aspects of executive functioning (Stroop and Berg tasks) in females but not in males. Ginseng had no effect on cognition. Ginkgo biloba in females reversed the initial (i.e. placebo) increase in cardiovascular reactivity (systolic and diastolic readings increased compared to baseline) to cognitive tasks. This effect (reversal) was most notable after those tasks (Stroop and Iowa) that elicited the greatest cardiovascular reactivity during placebo. In males, although ginkgo also decreased cardiovascular readings, it did so from an initial (placebo) blunted response (i.e. decrease or no change from baseline) to cognitive tasks. Ginseng, on the contrary, increased cardiovascular readings compared to placebo.
Conclusions/Significance
These results suggest that cardiovascular reactivity may be a mechanism by which ginkgo but not ginseng, in females is associated with certain forms of cognitive improvement
Climate policy for a net-zero future: ten recommendations for Direct Air Capture
Direct Air Capture with Carbon Storage (DACCS) technologies represent one of the most significant potential tools for tackling climate change by making net-zero and net-negative emissions achievable, as deemed necessary in reports from the Intergovernmental Panel on Climate Change and the European Green Deal. We draw from a novel and original dataset of expert interviews (N = 125) to distil ten recommendations for future DACCS policy. After providing a literature review on DACCS and explaining our methods of data collection, we present these recommendations as follows: (a) follow governance principles that ensure 'negative' emissions; (b) prioritize long-term carbon storage; (c) appreciate and incentivize scale; (d) co-develop with capture, transport, and storage; (e) phase in a carbon price; (f) couple with renewables; (g) harness hub deployment; (h) maintain separate targets; (i) embrace certification and compliance; and (j) recognize social acceptance. All ten recommendations are important, and all speak to the urgency and necessity of better managing and shaping the potentially impending DACCS transition
A synonymous codon variant in two patients with autosomal recessive bestrophinopathy alters in vitro splicing of BEST1
Purpose: Autosomal recessive bestrophinopathy (ARB) is a newly defined retinal dystrophy caused by biallelic mutations in bestrophin-1 (BEST1) and is hypothesized to represent the null bestrophin-1 phenotype in humans. The aim was to determine whether a synonymous BEST1 variant, c.102C>T, identified in two unrelated ARB patients, alters pre-mRNA splicing of the gene. Additionally a detailed phenotypic characterization of this distinctive condition is presented for both patients.Methods: BEST1 was analyzed by direct sequencing. Patients underwent standard ophthalmic assessment. In silico and in vitro analysis using a minigene system was performed to assess whether a synonymous variant identified, c.102C>T p.Gly34Gly, alters pre-mRNA splicing of BEST1.Results: Both ARB patients harbored either proven (patient 1; c.102C>T p.Gly34Gly and c.572T>C p.Leu191Pro) or presumed (patient 2; c.102C>T p.Gly34Gly and c.1470_1471delCA, p.His490GlnfsX24) biallelic mutations in BEST1 and were found to have phenotypes consistent with ARB. In vitro analysis of the synonymous variant, c.102C>T p.Gly34Gly, demonstrated it to introduce a cryptic splice donor site 52 nucleotides upstream of the actual splice donor site.Conclusions: The novel BEST1 variant identified, c.102C>T p.Gly34Gly, alters pre-mRNA splicing in vitro and is potentially pathogenic. In vivo this splicing variant is predicted to lead to the production of an mRNA transcript with a premature termination codon (p.Glu35TrpfsX11) that is predicted to be degraded by NMD
Exogenous NG-hydroxy-l-arginine causes nitrite production in vascular smooth muscle cells in the absence of nitric oxide synthase activity
AbstractNitric oxide (NO) production from exogenous NG-hydroxy-l-arginine (OH-l-Arg) was investigated in rat aortic smooth muscle cells in culture by measuring nitrite accumulation in the culture medium. As well, the interaction between OH-l-Arg and l-arginine uptake via the y+ cationic amino acid transporter was studied. In cells without NO-synthase activity, OH-l-Arg (1–1000 μM) induced a dose-dependent nitrite production with a half-maximal effective concentration (EC50) of 18.0 ± 1.5 μM (n = 4–7). This nitrite accumulation was not inhibited by the NO-synthase inhibitor NG-nitro-l-arginine methyl ester, l-NAME (300 μM). In contrast, it was abolished by miconazole (100 μM), an inhibitor of cytochrome P450. Incubation of vascular smooth muscle cells with LPS (10 μgml) induced an l-name inhibited nitrite accumulation, but did not enhance the OH-l-Arg induced nitrite production. OH-l-Arg and other cationic amino acids, L-lysine and l-ornithine, competitively inhibited [3H]-l-arginine uptake m rat aortic smooth muscle cells, with inhibition constants of 195 ± 23 μM(n = 12), 260 ± 40 μM(n= 5) and 330 ± 10 μM(n = 5), respectively. These results show that OH-l-Arg is recognized by the cationic l-amino acid carrier present in vascular smooth muscle cells and can be oxidized to NO and nitrite in these cells in the absence of NO-synthase, probably by cytochrome P450 or by a reaction involving a cytochrome P450 byproduct
Extension of the sum rule for the transition rates between multiplets to the multiphoton case
The sum rule for the transition rates between the components of two
multiplets, known for the one-photon transitions, is extended to the
multiphoton transitions in hydrogen and hydrogen-like ions. As an example the
transitions 3p-2p, 4p-3p and 4d-3d are considered. The numerical results are
compared with previous calculations.Comment: 10 pages, 4 table
Oxidised cosmic acceleration
We give detailed proofs of several new no-go theorems for constructing flat
four-dimensional accelerating universes from warped dimensional reduction.
These new theorems improve upon previous ones by weakening the energy
conditions, by including time-dependent compactifications, and by treating
accelerated expansion that is not precisely de Sitter. We show that de Sitter
expansion violates the higher-dimensional null energy condition (NEC) if the
compactification manifold M is one-dimensional, if its intrinsic Ricci scalar R
vanishes everywhere, or if R and the warp function satisfy a simple limit
condition. If expansion is not de Sitter, we establish threshold
equation-of-state parameters w below which accelerated expansion must be
transient. Below the threshold w there are bounds on the number of e-foldings
of expansion. If M is one-dimensional or R everywhere vanishing, exceeding the
bound implies the NEC is violated. If R does not vanish everywhere on M,
exceeding the bound implies the strong energy condition (SEC) is violated.
Observationally, the w thresholds indicate that experiments with finite
resolution in w can cleanly discriminate between different models which satisfy
or violate the relevant energy conditions.Comment: v2: corrections, references adde
Svestka's Research: Then and Now
Zdenek Svestka's research work influenced many fields of solar physics,
especially in the area of flare research. In this article I take five of the
areas that particularly interested him and assess them in a "then and now"
style. His insights in each case were quite sound, although of course in the
modern era we have learned things that he could not readily have envisioned.
His own views about his research life have been published recently in this
journal, to which he contributed so much, and his memoir contains much
additional scientific and personal information (Svestka, 2010).Comment: Invited review for "Solar and Stellar Flares," a conference in honour
of Prof. Zden\v{e}k \v{S}vestka, Prague, June 23-27, 2014. This is a
contribution to a Topical Issue in Solar Physics, based on the presentations
at this meeting (Editors Lyndsay Fletcher and Petr Heinzel
Interstellar MHD Turbulence and Star Formation
This chapter reviews the nature of turbulence in the Galactic interstellar
medium (ISM) and its connections to the star formation (SF) process. The ISM is
turbulent, magnetized, self-gravitating, and is subject to heating and cooling
processes that control its thermodynamic behavior. The turbulence in the warm
and hot ionized components of the ISM appears to be trans- or subsonic, and
thus to behave nearly incompressibly. However, the neutral warm and cold
components are highly compressible, as a consequence of both thermal
instability in the atomic gas and of moderately-to-strongly supersonic motions
in the roughly isothermal cold atomic and molecular components. Within this
context, we discuss: i) the production and statistical distribution of
turbulent density fluctuations in both isothermal and polytropic media; ii) the
nature of the clumps produced by thermal instability, noting that, contrary to
classical ideas, they in general accrete mass from their environment; iii) the
density-magnetic field correlation (or lack thereof) in turbulent density
fluctuations, as a consequence of the superposition of the different wave modes
in the turbulent flow; iv) the evolution of the mass-to-magnetic flux ratio
(MFR) in density fluctuations as they are built up by dynamic compressions; v)
the formation of cold, dense clouds aided by thermal instability; vi) the
expectation that star-forming molecular clouds are likely to be undergoing
global gravitational contraction, rather than being near equilibrium, and vii)
the regulation of the star formation rate (SFR) in such gravitationally
contracting clouds by stellar feedback which, rather than keeping the clouds
from collapsing, evaporates and diperses them while they collapse.Comment: 43 pages. Invited chapter for the book "Magnetic Fields in Diffuse
Media", edited by Elisabete de Gouveia dal Pino and Alex Lazarian. Revised as
per referee's recommendation
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