405 research outputs found
On the dynamics of solar polar plumes observed by SoHO/UVCS
We investigate the plasma outflow in solar polar plumes by using SoHO/UVCS observations of May 2005. Despite the fact that data have been acquired more than ten years ago, UVCS spectral observations in the intermediate corona still represent a unique opportunity of studying the plasma dynamics at those heliocentric distances. The Doppler dimming technique is applied to the O VI doublet and H I Lyman-α spectral lines, to infer the outflow speed and the electron density in plumes and interplumes. Our aim is to, investigate if plumes, in the intermediate corona, are to be considered static structures or if they dynamically expand, contributing to the fast solar wind
Morphology, dynamics and plasma parameters of plumes and inter-plume regions in solar coronal holes
Coronal plumes, which extend from solar coronal holes (CH) into the high
corona and - possibly - into the solar wind (SW), can now continuously be
studied with modern telescopes and spectrometers on spacecraft, in addition to
investigations from the ground, in particular, during total eclipses. Despite
the large amount of data available on these prominent features and related
phenomena, many questions remained unanswered as to their generation and
relative contributions to the high-speed streams emanating from CHs. An
understanding of the processes of plume formation and evolution requires a
better knowledge of the physical conditions at the base of CHs, in plumes and
in the surrounding inter-plume regions (IPR). More specifically, information is
needed on the magnetic field configuration, the electron densities and
temperatures, effective ion temperatures, non-thermal motions, plume
cross-sections relative to the size of a CH, the plasma bulk speeds, as well as
any plume signatures in the SW. In spring 2007, the authors proposed a study on
"Structure and dynamics of coronal plumes and inter-plume regions in solar
coronal holes" to the International Space Science Institute (ISSI) in Bern to
clarify some of these aspects by considering relevant observations and the
extensive literature. This review summarizes the results and conclusions of the
study. Stereoscopic observations allowed us to include three-dimensional
reconstructions of plumes. Multi-instrument investigations carried out during
several campaigns led to progress in some areas, such as plasma densities,
temperatures, plume structure and the relation to other solar phenomena, but
not all questions could be answered concerning the details of plume generation
process(es) and interaction with the SW.Comment: To appear on: The Astronomy and Astrophysics Review. 72 pages, 30
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Effect of reducing barley grain degradability on lambs weight, colostrum, milk production, their composition and some biochemical blood trats in Awassi ewes
This study was conducted in research department of animal resource / Al-Rashidiya, by using 21 of Awassi ewes in the last two months of gestation, ewes were divided according to their body weight, age and milk production during the previous season into three groups, daily feed intake in all groups was restricted with 1.5 kg / ewe on rations consist of barley, wheat bran, soybean meal, urea and straw. the first group was fed on ration contained barley untreated with formaldehyde (T1), while barley grain treated with formaldehyde in the ration of second group (T2), the third group fed on formaldehyde treated barley in late gestation and switch directly after lambing to the untreated barley (T3). Results indicated that differences was non-significant in colostrum yield 138±16.41, 163±19.26 and 127±19.43 g/ hr and in its components, milk yield was increased (P<0.05) in T2 1411±99.04 g/ day as compared with T1 and T2 1080±77.02 and 940±34.54 g/ day respectively, while no significant differences was noted in milk composition. Efficiency of protein and energy intake for milk production significantly higher (P<0.01) in T2 which were 26.42±2.01 and 42.24±3.55% compared to T1 (20.56±1.59 and 34.31±2.99%) and only in energy efficiency as compared with T3 which were (17.70±0.78 and 30.62±1.34%). Result of blood parameters after four week postpartum was indicated a significant (P<0.05) increase in cholesterol concentration in T1 69.60±4.85 mg/ dl compared to T2 and T3 56.55±3.67 and 54.73±3.99 mg/ dl, blood creatinine concentration decreased (P<0.05) in T3 5.03±0.53 mg/ dl as compared to T1 and T2 which were 9.60±0.77 and 9.35±0.53 mg/ dl respectively. In conclusion, reducing barley grain degradability improve feed efficiency and ewes performance, while the directly change of the feeding after lambing from low degraded barley to the normal barley grain had a negative effect in performance
Comparing extrapolations of the coronal magnetic field structure at 2.5 solar radii with multi-viewpoint coronagraphic observations
The magnetic field shapes the structure of the solar corona but we still know
little about the interrelationships between the coronal magnetic field
configurations and the resulting quasi-stationary structures observed in
coronagraphic images (as streamers, plumes, coronal holes). One way to obtain
information on the large-scale structure of the coronal magnetic field is to
extrapolate it from photospheric data and compare the results with
coronagraphic images. Our aim is to verify if this comparison can be a fast
method to check systematically the reliability of the many methods available to
reconstruct the coronal magnetic field. Coronal fields are usually extrapolated
from photospheric measurements typically in a region close to the central
meridian on the solar disk and then compared with coronagraphic images at the
limbs, acquired at least 7 days before or after to account for solar rotation,
implicitly assuming that no significant changes occurred in the corona during
that period. In this work, we combine images from three coronagraphs
(SOHO/LASCO-C2 and the two STEREO/SECCHI-COR1) observing the Sun from different
viewing angles to build Carrington maps covering the entire corona to reduce
the effect of temporal evolution to ~ 5 days. We then compare the position of
the observed streamers in these Carrington maps with that of the neutral lines
obtained from four different magnetic field extrapolations, to evaluate the
performances of the latter in the solar corona. Our results show that the
location of coronal streamers can provide important indications to discriminate
between different magnetic field extrapolations.Comment: Accepted by A&A the 20th of May, 201
Diversity of a cytokinin dehydrogenase gene in wild and cultivated barley
The cytokinin dehydrogenase gene HvCKX2.1 is the regulatory target for the most abundant heterochromatic small RNAs in drought-stressed barley caryopses. We investigated the diversity of HvCKX2.1 in 228 barley landraces and 216 wild accessions and identified 14 haplotypes, five of these with ten or more members, coding for four different protein variants. The third largest haplotype was abundant in wild accessions (51 members), but absent from the landrace collection. Protein structure predictions indicated that the amino acid substitution specific to haplotype 3 could result in a change in the functional properties of the HvCKX2.1 protein. Haplotypes 1–3 have overlapping geographical distributions in the wild population, but the average rainfall amounts at the collection sites for haplotype 3 plants are significantly higher during November to February compared to the equivalent data for plants of haplotypes 1 and 2. We argue that the likelihood that haplotype 3 plants were excluded from landraces by sampling bias that occurred when the first wild barley plants were taken into cultivation is low, and that it is reasonable to suggest that plants with haplotype 3 are absent from the crop because these plants were less suited to the artificial conditions associated with cultivation. Although the cytokinin signalling pathway influences many aspects of plant development, the identified role of HvCKX2.1 in the drought response raises the possibility that the particular aspect of cultivation that mitigated against haplotype 3 relates in some way to water utilization. Our results therefore highlight the possibility that water utilization properties should be looked on as a possible component of the suite of physiological adaptations accompanying the domestication and subsequent evolution of cultivated barley
At the end of cosmic noon: Short gas depletion times in unobscured quasars at 1
Unobscured quasars (QSOs) are predicted to be the final stage in the
evolutionary sequence from gas-rich mergers to gas-depleted, quenched galaxies.
Studies of this population, however, find a high incidence of
far-infrared-luminous sources -suggesting significant dust-obscured star
formation-but direct observations of the cold molecular gas fuelling this star
formation are still necessary. We present a NOEMA study of CO(2-1) emission,
tracing the cold molecular gas, in ten lensed z=1-1.5 unobscured QSOs. We
detected CO(2-1) in seven of our targets, four of which also show continuum
emission (\lambda_rest = 1.3mm). After subtracting the foreground galaxy
contribution to the photometry, spectral energy distribution fitting yielded
stellar masses of 10^9-11 M_\odot, with star formation rates of 25-160 M_\odot
yr^-1 for the host galaxies. These QSOs have lower than
star-forming galaxies with the same L_IR, and show depletion times spanning a
large range (50-900 Myr), but with a median of just 90 Myr. We find molecular
gas masses in the range 2-40 x 10^9(alpha_CO/4) M_\odot, which suggest gas
fractions above ~50% for most of the targets. Despite the presence of an
unobscured QSO, the host galaxies are able to retain significant amounts of
cold gas. However, with a median depletion time of ~90 Myr, the intense burst
of star formation taking place in these targets will quickly deplete their
molecular gas reservoirs in the absence of gas replenishment, resulting in a
quiescent host galaxy. The non-detected QSOs are three of the four radio-loud
QSOs in the sample, and their properties indicate that they are likely already
transitioning into quiescence. Recent cosmological simulations tend to
overestimate the depletion times expected for these z~1 QSO-host galaxies,
which is likely linked to their difficulty producing starbursts across the
general high-redshift galaxy population.Comment: 20 pages. Accepted for publication in A&
In-flight validation of Metis Visible-light Polarimeter Coronagraph on board Solar Orbiter
Context. The Metis coronagraph is one of the remote-sensing instruments of
the ESA/NASA Solar Orbiter mission. Metis is aimed at the study of the solar
atmosphere and solar wind by simultaneously acquiring images of the solar
corona at two different wavelengths; visible-light (VL) within a band ranging
from 580 nm to 640 nm, and in the HI Ly-alpha 121.6 +/- 10 nm ultraviolet (UV)
light. The visible-light channel includes a polarimeter with electro-optically
modulating Liquid Crystal Variable Retarders (LCVRs) to measure the linearly
polarized brightness of the K-corona to derive the electron density.
Aims. In this paper, we present the first in-flight validation results of the
Metis polarimetric channel together with a comparison to the on-ground
calibrations. It is the validation of the first use in deep space (with hard
radiation environment) of an electro-optical device: a liquid crystal-based
polarimeter.
Methods. We used the orientation of the K-corona's linear polarization vector
during the spacecraft roll maneuvers for the in-flight calibration.
Results. The first in-flight validation of the Metis coronagraph on-board
Solar Orbiter shows a good agreement with the on-ground measurements. It
confirms the expected visible-light channel polarimetric performance. A final
comparison between the first pB obtained by Metis with the polarized brightness
(pB) obtained by the space-based coronagraph LASCO and the ground-based
coronagraph KCor shows the consistency of the Metis calibrated results.Comment: 8 pages, 13 figures, 3 tables, pape
Quantitative trait loci conferring grain mineral nutrient concentrations in durum wheat 3 wild emmer wheat RIL population
Mineral nutrient malnutrition, and particularly
deficiency in zinc and iron, afflicts over 3 billion people
worldwide. Wild emmer wheat, Triticum turgidum ssp.
dicoccoides, genepool harbors a rich allelic repertoire for
mineral nutrients in the grain. The genetic and physiological
basis of grain protein, micronutrients (zinc, iron,
copper and manganese) and macronutrients (calcium,
magnesium, potassium, phosphorus and sulfur) concentration
was studied in tetraploid wheat population of 152
recombinant inbred lines (RILs), derived from a cross
between durum wheat (cv. Langdon) and wild emmer
(accession G18-16). Wide genetic variation was found
among the RILs for all grain minerals, with considerable
transgressive effect. A total of 82 QTLs were mapped for
10 minerals with LOD score range of 3.2–16.7. Most QTLs
were in favor of the wild allele (50 QTLs). Fourteen pairs
of QTLs for the same trait were mapped to seemingly
homoeologous positions, reflecting synteny between the A
and B genomes. Significant positive correlation was found
between grain protein concentration (GPC), Zn, Fe and Cu,
which was supported by significant overlap between the
respective QTLs, suggesting common physiological and/or
genetic factors controlling the concentrations of these
mineral nutrients. Few genomic regions (chromosomes 2A,
5A, 6B and 7A) were found to harbor clusters of QTLs for
GPC and other nutrients. These identified QTLs may
facilitate the use of wild alleles for improving grain
nutritional quality of elite wheat cultivars, especially in
terms of protein, Zn and Fe
METIS: the visible and UV coronagraph for Solar Orbiter
METIS coronagraph is designed to observe the solar corona with an annular field of view from 1.5 to 2.9 degrees in the visible broadband (580-640 nm) and in the UV HI Lyman-alpha, during the Sun close approaching and high latitude tilting orbit of Solar Orbiter. The big challenge for a coronagraph is the stray light rejection. In this paper after a description of the present METIS optical design, the stray light rejection design is presented in detail together with METIS off-pointing strategies throughout the mission. Data shown in this paper derive from the optimization of the optical design performed with Zemax ray tracing and from laboratory breadboards of the occultation system and of the polarimeter
A high-latitude coronal mass ejection observed by a constellation of coronagraphs: Solar Orbiter/Metis, STEREO-A/COR2, and SOHO/LASCO
Context. A few days before the first perihelion of the Solar Orbiter nominal mission, which occurred on 2022 March 26, the Metis coronagraph on board Solar Orbiter detected a coronal mass ejection (CME) that was moving away from the far side of the Sun (with respect to Solar Orbiter) at high northern latitudes. The eruption was also seen by other spacecraft, in particular, by STEREO-A, which was in quadrature configuration with Solar Orbiter. Aims. We analyse the different views of the CME by a constellation of spacecraft with the purpose to determine the speed and acceleration of the CME, and to identify the source region of the CME. Methods. Considering the positions of various spacecraft on 2022 March 22, this CME happened to be within the field of view of STEREO-A/SECCHI, and it was visible over the limb from SOHO/LASCO. We present the results of the 3D reconstruction of the CME based on the graduated cylindrical shell model and of the identification of the possible origin of the CME using extreme-ultraviolet (EUV) observations by Solar Orbiter/EUI, STEREO-A/EUVI, and SDO/AIA. The observations in EUV are compared with the coronal magnetic structure obtained by the potential field source surface method. Results. The 3D reconstruction of the CME derives a central latitude of 29 N, a Stonyhurst longitude of 125, and an average radial speed at the apex of 322 ± 33 km s1 between 4 and 13 RȮ, which is probably not high enough to generate a shock wave. The estimated average acceleration of the CME is 16 ± 11 m s2 in the same range of distances from the Sun. This CME may be associated with the disappearance of a coronal cloud prominence, which is seen in the EUV by STEREO-A/EUVI and SDO/AIA, and is also associated with rapidly evolving emerging magnetic flux
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