640 research outputs found
The sequence of rice chromosomes 11 and 12, rich in disease resistance genes and recent gene duplications
Background: Rice is an important staple food and, with the smallest cereal genome, serves as a reference species for studies on the evolution of cereals and other grasses. Therefore, decoding its entire genome will be a prerequisite for applied and basic research on this species and all other cereals. Results: We have determined and analyzed the complete sequences of two of its chromosomes, 11 and 12, which total 55.9 Mb (14.3% of the entire genome length), based on a set of overlapping clones. A total of 5,993 non-transposable element related genes are present on these chromosomes. Among them are 289 disease resistance-like and 28 defense-response genes, a higher proportion of these categories than on any other rice chromosome. A three-Mb segment on both chromosomes resulted from a duplication 7.7 million years ago (mya), the most recent large-scale duplication in the rice genome. Paralogous gene copies within this segmental duplication can be aligned with genomic assemblies from sorghum and maize. Although these gene copies are preserved on both chromosomes, their expression patterns have diverged. When the gene order of rice chromosomes 11 and 12 was compared to wheat gene loci, significant synteny between these orthologous regions was detected, illustrating the presence of conserved genes alternating with recently evolved genes. Conclusion: Because the resistance and defense response genes, enriched on these chromosomes relative to the whole genome, also occur in clusters, they provide a preferred target for breeding durable disease resistance in rice and the isolation of their allelic variants. The recent duplication of a large chromosomal segment coupled with the high density of disease resistance gene clusters makes this the most recently evolved part of the rice genome. Based on syntenic alignments of these chromosomes, rice chromosome 11 and 12 do not appear to have resulted from a single whole-genome duplication event as previously suggested
Gendering the careers of young professionals: some early findings from a longitudinal study. in Organizing/theorizing: developments in organization theory and practice
Wonders whether companies actually have employees best interests at heart across physical, mental and spiritual spheres. Posits that most organizations ignore their workforce – not even, in many cases, describing workers as assets! Describes many studies to back up this claim in theis work based on the 2002 Employment Research Unit Annual Conference, in Cardiff, Wales
Follow-up of multi-messenger alerts with the KM3NeT ARCA and ORCA detectors
The strength of multi-messenger astronomy comes from its capability to increase the significance of a detection through the combined observation of events coincident in space and time. This is particularly valuable for transient events, since the use of a narrow time window can allow a reduction of background of the search.
In KM3NeT, we are actively monitoring and analysing a variety of external triggers in real-time, including alerts like IceCube neutrinos, HAWC gamma-ray transients, LIGO-Virgo- KAGRA gravitational waves, SNEWS neutrino alerts, and others.
In this contribution, we present the follow-up of various external alerts using the comple- mentary capabilities of the two KM3NeT detectors, ORCA (covering the few GeV to few TeV energy range) and ARCA (ranging from sub-TeV energies up to tens of PeV). Both detectors were collecting high-quality data with partial configurations during the period of the studied alerts, which goes from December 2021 until June 2023
Constraints on the intergalactic magnetic field using Fermi-LAT and H.E.S.S. blazar observations
Magnetic fields in galaxies and galaxy clusters are believed to be the result
of the amplification of intergalactic seed fields during the formation of
large-scale structures in the universe. However, the origin, strength, and
morphology of this intergalactic magnetic field (IGMF) remain unknown. Lower
limits on (or indirect detection of) the IGMF can be obtained from observations
of high-energy gamma rays from distant blazars. Gamma rays interact with the
extragalactic background light to produce electron-positron pairs, which can
subsequently initiate electromagnetic cascades. The -ray signature of
the cascade depends on the IGMF since it deflects the pairs. Here we report on
a new search for this cascade emission using a combined data set from the Fermi
Large Area Telescope and the High Energy Stereoscopic System. Using
state-of-the-art Monte Carlo predictions for the cascade signal, our results
place a lower limit on the IGMF of G for a coherence
length of 1 Mpc even when blazar duty cycles as short as 10 yr are assumed.
This improves on previous lower limits by a factor of 2. For longer duty cycles
of () yr, IGMF strengths below G
( G) are excluded, which rules out specific models for IGMF
generation in the early universe.Comment: 20 pages, 7 figures, 4 tables. Accepted for publication in ApJ
Letters. Auxiliary data is provided in electronic format at
https://zenodo.org/record/801431
Limits on the nuclearite flux using the ANTARES neutrino telescope
In this work, a search for nuclearites of strange quark matter by using nine
years of ANTARES data taken in the period 2009-2017 is presented. The passage
through matter of these particles is simulated %according to the model of de
R\'{u}jula and Glashow taking into account a detailed description of the
detector response to nuclearites and of the data acquisition conditions. A
down-going flux of cosmic nuclearites with Galactic velocities () was considered for this study. The mass threshold for detecting these
particles at the detector level is \mbox{ GeV/c}.
Upper limits on the nuclearite flux for masses up to GeV/c at
the level of cm s sr are
obtained. These are the first upper limits on nuclearites established with a
neutrino telescope and the most stringent ever set for Galactic velocities.Comment: 17 pages, 7 figure
TeV flaring activity of the AGN PKS 0625-354 in November 2018
Most -ray detected active galactic nuclei are blazars with one of
their relativistic jets pointing towards the Earth. Only a few objects belong
to the class of radio galaxies or misaligned blazars. Here, we investigate the
nature of the object PKS 0625-354, its -ray flux and spectral
variability and its broad-band spectral emission with observations from
H.E.S.S., Fermi-LAT, Swift-XRT, and UVOT taken in November 2018. The H.E.S.S.
light curve above 200 GeV shows an outburst in the first night of observations
followed by a declining flux with a halving time scale of 5.9h. The
-opacity constrains the upper limit of the angle between the jet
and the line of sight to . The broad-band spectral energy
distribution shows two humps and can be well fitted with a single-zone
synchrotron self Compton emission model. We conclude that PKS 0625-354, as an
object showing clear features of both blazars and radio galaxies, can be
classified as an intermediate active galactic nuclei. Multi-wavelength studies
of such intermediate objects exhibiting features of both blazars and radio
galaxies are sparse but crucial for the understanding of the broad-band
emission of -ray detected active galactic nuclei in general.Comment: 9 pages, 6 figures, accepted for publication in Astronomy &
Astrophysic
Review of the online analyses of multi-messenger alerts and electromagnetic transient events with the ANTARES neutrino telescope
By constantly monitoring a very large portion of the sky, neutrino telescopes are well-designed to detect neutrinos emitted by transient astrophysical events. Real-time searches with the ANTARES telescope have been performed to look for neutrino candidates coincident with gamma-ray bursts detected by the Swift and Fermi satellites, high-energy neutrino events registered by IceCube, transient events from blazars monitored by HAWC, photon-neutrino coincidences by AMON notices and gravitational wave candidates observed by LIGO/Virgo. By requiring temporal coincidence, this approach increases the sensitivity and the significance of a potential discovery. This paper summarises the results of the followup performed of the ANTARES telescope between January 2014 and February 2022, which corresponds to the end of the data-taking period
Acoustic Positioning for Deep Sea Neutrino Telescopes with a System of Piezo Sensors Integrated into Glass Spheres
Position calibration in the deep sea is typically done by means of acoustic
multilateration using three or more acoustic emitters installed at known
positions. Rather than using hydrophones as receivers that are exposed to the
ambient pressure, the sound signals can be coupled to piezo ceramics glued to
the inside of existing containers for electronics or measuring instruments of a
deep sea infrastructure. The ANTARES neutrino telescope operated from 2006
until 2022 in the Mediterranean Sea at a depth exceeding 2000m. It comprised
nearly 900 glass spheres with 432mm diameter and 15mm thickness, equipped with
photomultiplier tubes to detect Cherenkov light from tracks of charged
elementary particles. In an experimental setup within ANTARES, piezo sensors
have been glued to the inside of such - otherwise empty - glass spheres. These
sensors recorded signals from acoustic emitters with frequencies from 46545 to
60235Hz. Two waves propagating through the glass sphere are found as a result
of the excitation by the waves in the water. These can be qualitatively
associated with symmetric and asymmetric Lamb-like waves of zeroth order: a
fast (early) one with mm/s and a slow (late) one with
mm/s. Taking these findings into account improves the
accuracy of the position calibration. The results can be transferred to the
KM3NeT neutrino telescope, currently under construction at multiple sites in
the Mediterranean Sea, for which the concept of piezo sensors glued to the
inside of glass spheres has been adapted for monitoring the positions of the
photomultiplier tubes.Comment: submitted to "Experimental Astronomy
Search for neutrino counterparts to the gravitational wave sources from O3 catalogues with the ANTARES detector
Since 2015 the LIGO and Virgo interferometers have detected gravitational
waves from almost one hundred coalescences of compact objects (black holes and
neutron stars). This article presents the results of a search performed with
data from the ANTARES telescope to identify neutrino counterparts to the
gravitational wave sources detected during the third LIGO/Virgo observing run
and reported in the catalogues GWTC-2, GWTC-2.1, and GWTC-3. This search is
sensitive to all-sky neutrinos of all flavours and of energies GeV,
thanks to the inclusion of both track-like events (mainly induced by
charged-current interactions) and shower-like events (induced by other
interaction types). Neutrinos are selected if they are detected within s from the GW merger and with a reconstructed direction compatible with
its sky localisation. No significant excess is found for any of the 80 analysed
GW events, and upper limits on the neutrino emission are derived. Using the
information from the GW catalogues and assuming isotropic emission, upper
limits on the total energy and on the fraction of the total
energy budget emitted as neutrinos of
all flavours are also computed. Finally, a stacked analysis of all the 72
binary black hole mergers (respectively the 7 neutron star - black hole merger
candidates) has been performed to constrain the typical neutrino emission
within this population, leading to the limits: erg and (respectively, erg and ) for spectrum and isotropic emission.
Other assumptions including softer spectra and non-isotropic scenarios have
also been tested.Comment: 13 pages, 4 figure
Review of the online analyses of multi-messenger alerts and electromagnetic transient events with the ANTARES neutrino telescope
By constantly monitoring at least one complete hemisphere of the sky,
neutrino telescopes are well designed to detect neutrinos emitted by transient
astrophysical events. Real-time searches with the ANTARES telescope have been
performed to look for neutrino candidates coincident with gamma-ray bursts
detected by the Swift and Fermi satellites, highenergy neutrino events
registered by IceCube, transient events from blazars monitored by HAWC,
photon-neutrino coincidences by AMON notices and gravitational wave candidates
observed by LIGO/Virgo. By requiring temporal coincidence, this approach
increases the sensitivity and the significance of a potential discovery. Thanks
to the good angular accuracy of neutrino candidates reconstructed with the
ANTARES telescope, a coincident detection can also improve the positioning area
of non-well localised triggers such as those detected by gravitational wave
interferometers. This paper summarises the results of the follow-up performed
by the ANTARES telescope between 01/2014 and 02/2022, which corresponds to the
end of the data taking period.Comment: 21 pages, 10 figures, JCAP08 (2023) 072 (19 p
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