9 research outputs found
Multiple roles for UV RESISTANCE LOCUS8 in regulating gene expression and metabolite accumulation in arabidopsis under solar ultraviolet radiation
Photomorphogenic responses triggered by low fluence rates of ultraviolet B radiation (UV-B; 280–315 nm) are mediated by the UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8). Beyond our understanding of the molecular mechanisms of UV-B perception by UVR8, there is still limited information on how the UVR8 pathway functions under natural sunlight. Here, wild-type Arabidopsis (Arabidopsis thaliana) and the uvr8-2 mutant were used in an experiment outdoors where UV-A (315–400 nm) and UV-B irradiances were attenuated using plastic films. Gene expression, PYRIDOXINE BIOSYNTHESIS1 (PDX1) accumulation, and leaf metabolite signatures were analyzed. The results show that UVR8 is required for transcript accumulation of genes involved in UV protection, oxidative stress, hormone signal transduction, and defense against herbivores under solar UV. Under natural UV-A irradiance, UVR8 is likely to interact with UV-A/blue light signaling pathways to moderate UV-B-driven transcript and PDX1 accumulation. UVR8 both positively and negatively affects UV-A-regulated gene expression and metabolite accumulation but is required for the UV-B induction of phenolics. Moreover, UVR8-dependent UV-B acclimation during the early stages of plant development may enhance normal growth under long-term exposure to solar UV
Beyond the visible: A handbook of best practice in plant UV photobiology.
The writing of this handbook started 14 months ago and is the results of the work of six editors and sixteen authors. This version is a preprint prepared for the participants in the 2012 training school of the COST action 5 FA0906 ‘UV4growth’ at University of Málaga. We hope that you find the handbook useful, and that you will alert us of errors, and of difficult to understand sections or paragraphs. Please, send all such comments to mailto:[email protected]?subject=TG1HandbookPre01feedback indicating page and line numbers. Many thanks for your help
Tunneling current modulation in atomically precise graphene nanoribbon heterojunctions
Lateral heterojunctions of atomically precise graphene nanoribbons GNRs hold promise for applications in nanotechnology, yet their charge transport and most of the spectroscopic properties have not been investigated. Here, we synthesize a monolayer of multiple aligned heterojunctions consisting of quasi metallic and wide bandgap GNRs, and report characterization by scanning tunneling microscopy, angle resolved photoemission, Raman spectroscopy, and charge transport. Comprehensive transport measurements as a function of bias and gate voltages, channel length, and temperature reveal that charge transport is dictated by tunneling through the potential barriers formed by wide bandgap GNR segments. The current voltage characteristics are in agreement with calculations of tunneling conductance through asymmetric barriers. We fabricate a GNR heterojunctions based sensor and demonstrate greatly improved sensitivity to adsorbates compared to graphene based sensors. This is achieved via modulation of the GNR heterojunction tunneling barriers by adsorbate
One-Step Synthesis of the Polyaniline–Single-Walled Carbon Tubes Nanocomposite in Formic Acid and Its Electrochemical Properties
An Effect of a Support Nature and Active Phase Morphology on Catalytic Properties of Ni-Containing Catalysts in Hydrogenation of Biphenyl
Primary black hole spin in oj 287 AS determined by the general relativity centenary flare
OJ 287 is a quasi-periodic quasar with roughly 12 year optical cycles. It displays prominent outbursts that are predictable in a binary black hole model. The model predicted a major optical outburst in 2015 December. We found that the outburst did occur within the expected time range, peaking on 2015 December 5 at magnitude 12.9 in the optical R-band. Based on Swift/XRT satellite measurements and optical polarization data, we find that it included a major thermal component. Its timing provides an accurate estimate for the spin of the primary black hole, . The present outburst also confirms the established general relativistic properties of the system such as the loss of orbital energy to gravitational radiation at the 2% accuracy level, and it opens up the possibility of testing the black hole no-hair theorem with 10% accuracy during the present decade. © 2016. The American Astronomical Society. All rights reserved
A search for QPOs in the blazar OJ287: Preliminary results from the 2015/2016 observing campaign
We analyse the light curve in the R band of the blazar OJ287, gathered during the 2015/2016 observing season. We did a search for quasi-periodic oscillations (QPOs) using several methods over a wide range of timescales. No statistically significant periods were found in the high-frequency domain both in the ground-based data and in Kepler observations. In the longer-period domain, the Lomb-Scargle periodogram revealed several peaks above the 99% significance level. The longest one-about 95 days-corresponds to the innermost stable circular orbit (ISCO) period of the more massive black hole. The 43-day period could be an alias, or it can be attributed to accretion in the form of a two-armed spiral wave. © 2016 by the authors
Searches for Dark Matter annihilation signatures in the Segue 1 satellite galaxy with the MAGIC-I telescope
We report the results of the observation of the nearby satellite galaxy Segue
1 performed by the MAGIC-I ground-based gamma-ray telescope between November
2008 and March 2009 for a total of 43.2 hours. No significant gamma-ray
emission was found above the background. Differential upper limits on the
gamma-ray flux are derived assuming various power-law slopes for the possible
emission spectrum. Integral upper limits are also calculated for several
power-law spectra and for different energy thresholds. The values are of the
order of 10^{-11} ph cm^{-2}$ s^{-1} above 100 GeV and 10^{-12} ph cm^{-2}
s^{-1} above 200 GeV. Segue 1 is currently considered one of the most
interesting targets for indirect dark matter searches. In these terms, the
upper limits have been also interpreted in the context of annihilating dark
matter particles. For such purpose, we performed a grid scan over a reasonable
portion of the parameter space for the minimal SuperGravity model and computed
the flux upper limit for each point separately, taking fully into account the
peculiar spectral features of each model. We found that in order to match the
experimental upper limits with the model predictions, a minimum flux boost of
10^{3} is required, and that the upper limits are quite dependent on the shape
of the gamma-ray energy spectrum predicted by each specific model. Finally we
compared the upper limits with the predictions of some dark matter models able
to explain the PAMELA rise in the positron ratio, finding that Segue 1 data are
in tension with the dark matter explanation of the PAMELA spectrum in the case
of a dark matter candidate annihilating into tau+tau-. A complete exclusion
however is not possible due to the uncertainties in the Segue 1 astrophysical
factor.Comment: 26 pages, 10 figures. Matched to published versio