1,873 research outputs found
An automated classification approach to ranking photospheric proxies of magnetic energy build-up
We study the photospheric magnetic field of ~2000 active regions in solar
cycle 23 to search for parameters indicative of energy build-up and subsequent
release as a solar flare. We extract three sets of parameters: snapshots in
space and time- total flux, magnetic gradients, and neutral lines; evolution in
time- flux evolution; structures at multiple size scales- wavelet analysis.
This combines pattern recognition and classification techniques via a relevance
vector machine to determine whether a region will flare. We consider
classification performance using all 38 extracted features and several feature
subsets. Classification performance is quantified using both the true positive
rate and the true negative rate. Additionally, we compute the true skill score
which provides an equal weighting to true positive rate and true negative rate
and the Heidke skill score to allow comparison to other flare forecasting work.
We obtain a true skill score of ~0.5 for any predictive time window in the
range 2-24hr, with a TPR of ~0.8 and a TNR of ~0.7. These values do not appear
to depend on the time window, although the Heidke skill score (<0.5) does.
Features relating to snapshots of the distribution of magnetic gradients show
the best predictive ability over all predictive time windows. Other
gradient-related features and the instantaneous power at various wavelet scales
also feature in the top five ranked features in predictive power. While the
photospheric magnetic field governs the coronal non-potentiality (and
likelihood of flaring), photospheric magnetic field alone is not sufficient to
determine this uniquely. Furthermore we are only measuring proxies of the
magnetic energy build up. We still lack observational details on why energy is
released at any particular point in time. We may have discovered the natural
limit of the accuracy of flare predictions from these large scale studies
Logarithmic entropy--corrected holographic dark energy with non--minimal kinetic coupling
In this paper, we have considered a cosmological model with the non--minimal
kinetic coupling terms and investigated its cosmological implications with
respect to the logarithmic entropy-- corrected holographic dark energy
(LECHDE). The correspondence between LECHDE in flat FRW cosmology and the
phantom dark energy model with the aim to interpret the current universe
acceleration is also examined.Comment: 11 pages, 2 figures; Can. J. Phys. Vol. 90, 201
Reconstructing a String-Inspired Non-minimally Coupled Quintom Model
Motivated by the recent work of Zhang and Chen \cite{bin}, we generalize
their work to the non-minimally coupled case. We consider a quintom model of
dark energy with a single scalar field given by a Lagrangian which inspired
by tachyonic Lagrangian in string theory. We consider non-minimal coupling of
tachyon field to the scalar curvature, then we reconstruct this model in the
light of three forms of parametrization for dynamical dark energy.Comment: 12 pages, 5 figure
Effects of acupressure at the hugo point (LI4) on labor pain and duration of delivery in nulliparous women
Introduction: Most women have experienced child birth and its pain, which is inevitable. If this pain is not controlled it leads to prolonged labor and injury to the mother and fetus. This study was conducted to identify the effect of acupressure on sanyinjiao and hugo points on delivery pain in nulliparous women. Methods:This was a randomized controlled clinical trial on 84 nulliparous women in hospitals of Ardebil, Iran. The participants were divided by randomized blocks of 4 and 6 into two groups. The intervention was in the form of applying pressure at sanyinjiao and hugo points based on different dilatations. The intensity of the pain before and after the intervention was recorded by visual scale of pain assessment. To determine the effect of pressure on the intensity of labor pain, analytical descriptive test was conducted in SPSS (version 13). Results:There was a significant decrease in mean intensity of pain after each intervention in the experimental group with different dilatations (4, 6, 8, and 10 cm). Moreover, the Student’s independent t-test results indicated that the mean intensity of pain in the experimental group after the intervention in all four dilatations was significantly lower than the control group. Repeated measures ANOVA test indicated that in both experimental and control groups in four time periods, there was a statistically significant difference. Conclusion:Acupressure on sanyinjiao and hugo points decreases the labor pain. Therefore, this method can be used effectively in the labor process
The orbit method solution for the deformed three coupled scalar fields
In this work, we present a deformed solutions starting from systems of three
coupled scalar fields with super-potential by orbit
method. First, we deform the corresponding super-potential and obtain defect
solutions. It is shown that how to construct new models altogether with its
defect solutions in terms of the non-deformed model. Therefore, we draw the
graph of super-potential and different fields in terms of So we observe
that the graphs for deformed and non - deformed cases are changed by the scale.Comment: 9 pages, 5 figure
Flatworms have lost the right open reading frame kinase 3 gene during evolution
All multicellular organisms studied to date have three right open reading frame kinase genes (designated riok-1, riok-2 and riok-3). Current evidence indicates that riok-1 and riok-2 have essential roles in ribosome biosynthesis, and that the riok-3 gene assists this process. In the present study, we conducted a detailed bioinformatic analysis of the riok gene family in 25 parasitic flatworms (platyhelminths) for which extensive genomic and transcriptomic data sets are available. We found that none of the flatworms studied have a riok-3 gene, which is unprecedented for multicellular organisms. We propose that, unlike in other eukaryotes, the loss of RIOK-3 from flatworms does not result in an evolutionary disadvantage due to the unique biology and physiology of this phylum. We show that the loss of RIOK-3 coincides with a loss of particular proteins associated with essential cellular pathways linked to cell growth and apoptosis. These findings indicate multiple, key regulatory functions of RIOK-3 in other metazoan species. Taking advantage of a known partial crystal structure of human RIOK-1, molecular modelling revealed variability in nucleotide binding sites between flatworm and human RIOK proteins
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