454 research outputs found
Identication of linear slow sausage waves in magnetic pores
The analysis of an 11-hour series of high resolution white light observations of a large pore in the sunspot group NOAA 7519, observed on 5 June 1993 with the Swedish Vacuum Solar Telescope at La Palma on Canary Islands, has been recently described by Dorotovič et al. (2002). Special attention was paid to the evolution of a filamentary region attached to the pore, to horizontal motions around the pore, and to small-scale morphological changes. One of the results, relevant to out work here, was the determination of temporal area evolution of the studied pore where the area itself showed a linear trend of decrease with time at an average rate of −0.23 Mm2h−1 during the entire observing period. Analysing the time series of the are of the pore, there is strong evidence that coupling between the solar interior and magnetic atmosphere can occur at various scales and that the referred decrease of the area may be connected with a decrease of the magnetic field strength according to the magnetic field-to-size relation. Periods of global acoustic, e.g. p-mode, driven waves are usually in the range of 5–10 minutes, and are favourite candidates for the coupling of interior oscillations with atmospheric dynamics. However, by assuming that magneto-acoustic gravity waves may be there too, and may act as drivers, the observed periodicities (frequencies) are expected to be much longer (smaller), falling well within the mMHz domain. In this work we determine typical periods of such range in the area evolution of the pore using wavelet analysis. The resulted periods are in the range of 20–70 minutes, suggesting that periodic elements of the temporal evolution of the area of this studied pore could be linked to, and considered as, observational evidence of linear low-frequency slow sausage (magneto-acoustic gravity) waves in magnetic pores. This would give us further evidence on the coupling of global solar oscillations to the overlaying magnetic atmosphere
Brightness, distribution, and evolution of sunspot umbral dots
We present a 106-minute TiO (705.7nm) time series of high spatial and
temporal resolution that contains thousands of umbral dots (UDs) in a mature
sunspot in the active region NOAA 10667 at =0.95. The data were acquired
with the 1-m Swedish Solar Telescope on La Palma. With the help of a multilevel
tracking (MLT) algorithm the sizes, brightnesses, and trajectories of 12836
umbral dots were found and analyzed. The MLT allows UDs with very low contrast
to be reliably identified. Inside the umbra we determine a UD filling factor of
11%. The histogram of UD lifetimes is monotonic, i.e. a UD does not have a
typical lifetime. Three quarters of the UDs lived for less than 150s and showed
no or little motion. The histogram of the UD diameters exhibits a maximum at
225km, i.e. most of the UDs are spatially resolved. UDs display a typical
horizontal velocity of 420m/s and a typical peak intensity of 51% of the mean
intensity of the quiet photosphere, making them on average 20% brighter than
the local umbral background. Almost all mobile UDs (large birth-death distance)
were born close to the umbra-penumbra boundary, move towards the umbral center,
and are brighter than average. Notably bright and mobile UDs were also observed
along a prominent UD chain, both ends of which are located at the
umbra-penumbra boundary. Their motion started primarily at either of the ends
of the chain, continued along the chain, and ended near the chain's center. We
observed the splitting and merging of UDs and the temporal succession of both.
For the first time the evolution of brightness, size, and horizontal speed of a
typical UD could be determined in a statistically significant way. Considerable
differences between the evolution of central and peripheral UDs are found,
which point to a difference in origin
Properties of Umbral Dots as Measured from the New Solar Telescope Data and MHD Simulations
We studied bright umbral dots (UDs) detected in a moderate size sunspot and
compared their statistical properties to recent MHD models. The study is based
on high resolution data recorded by the New Solar Telescope at the Big Bear
Solar Observatory and 3D MHD simulations of sunspots. Observed UDs, living
longer than 150 s, were detected and tracked in a 46 min long data set, using
an automatic detection code. Total 1553 (620) UDs were detected in the
photospheric (low chromospheric) data. Our main findings are: i) none of the
analyzed UDs is precisely circular, ii) the diameter-intensity relationship
only holds in bright umbral areas, and iii) UD velocities are inversely related
to their lifetime. While nearly all photospheric UDs can be identified in the
low chromospheric images, some small closely spaced UDs appear in the low
chromosphere as a single cluster. Slow moving and long living UDs seem to exist
in both the low chromosphere and photosphere, while fast moving and short
living UDs are mainly detected in the photospheric images. Comparison to the 3D
MHD simulations showed that both types of UDs display, on average, very similar
statistical characteristics. However, i) the average number of observed UDs per
unit area is smaller than that of the model UDs, and ii) on average, the
diameter of model UDs is slightly larger than that of observed ones.Comment: Accepted by the AP
IDENTIFIKACE ODRŮD ŘEPKY OLEJNÉ POUŽITÍM AFLP MARKERŮ
A new type of molecular marker, fluorescence-based AFLP, was evaluated for its ability to identify oilseed rape cultivars. Each of the six tested AFLP combinations detected polymorphisms, the best combination (MCAA/ E-ACT) had 26% of polymorphic peaks from a total of 90 peaks and could distinguish analysed cultivars, and 4 out of 5 DH lines. The results presented here show that florescence-based AFLP was, for the purposes of oil seed rape cultivar fingerprinting, a very suitable approach.Nový typ molekulárního markeru AFLP, založeného na fluorescenci, byl používán pro svou schopnost identifikovat odrůdy a homogenitu DH linií řepky olejné. Každá ze šesti testovaných AFLP kombinací
detekovala polymorfismy, nejlepší kombinace (M-CAA/E-ACT) měla 26% polymorfních píků z celkového počtu 90 a bylo možné rozlišit analyzované odrůdy a 4 z 5 DH linií. Genetická podobnost byla vypočítána použitím klastrové analýzy (metody UPGMA). Ukázalo se, že genetická podobnost mezi DH liniemi je nízká, i když tyto linie byly získány mikrosporogenezí. PCO analýza odrůd ukázala dva uzavřené klastery. Pouze u odrůdy Arabela byla zaznamenána větší odlišnost
Age, gender and COVID-19 infections
Data for ten European countries which provide detailed distribution of COVID-19 cases by sex and age show that among people of working age, women diagnosed with COVID-19 substantially outnumber infected men. This pattern reverses around retirement: infection rates among women fall at age 60-69, resulting in a cross-over with infection rates among men. The relative disadvantage of women peaks at ages 20-29, whereas the male disadvantage in infection rates peaks at ages 70-79. The elevated infection rates among women of working age are likely tied to their higher share in health- and care-related occupations. Our examination also suggests a link between women's employment profiles and infection rates in prime working ages. The same factors that determine women's higher life expectancy account for their lower fatality and higher male disadvantage at older ages
IMF isotopic properties in semi-peripheral collisions at Fermi energies
We study the neutron and proton dynamical behavior along the fragmentation
path in semi-peripheral collisions: 58Fe+58Fe (charge asymmetric, N/Z = 1.23)
and 58Ni+58Ni (charge symmetric, N/Z = 1.07), at 47 AMeV. We observe that
isospin dynamics processes take place also in the charge-symmetric system
58Ni+58Ni, that may produce more asymmetric fragments. A neutron enrichment of
the neck fragments is observed, resulting from the interplay between
pre-equilibrium emission and the phenomenon of "isospin-migration". Both
effects depend on the EoS (Equation of State) symmetry term. This point is
illustrated by comparing the results obtained with two different choices of the
symmetry energy density dependence.
New correlation observables are suggested, to study the reaction mechanism
and the isospin dynamics.Comment: 5 pages, 8 figures, Revtex4 Latex Styl
Three-body decay of Be
Three-body correlations for the ground-state decay of the lightest two-proton
emitter Be are studied both theoretically and experimentally. Theoretical
studies are performed in a three-body hyperspherical-harmonics cluster model.
In the experimental studies, the ground state of Be was formed following
the decay of a C beam inelastically excited through
interactions with Be and C targets. Excellent agreement between theory and
experiment is obtained demonstrating the existence of complicated correlation
patterns which can elucidate the structure of Be and, possibly, of the
A=6 isobar.Comment: 17 pages, 21 figures, 5 table
Central Iliac Arteriovenous Anastomosis for Hypertension: Targeting Mechanical Aspects of the Circulation
Dr. Lobo reports personal fees from ROX Medical, St Jude Medical, and Cardiosonic, and grants from Medtronic. Dr. Stanton reports that ROX Medical funded the ROX CONTROL HTN study. Dr. Sobotka reports personal fees and equity from ROX Medical; equity in Cibiem, Ablative Solutions, and Rainbow Medical; and personal fees from Abbott Ventures and Boston Scientific
- …