299 research outputs found
Variable stars with the Kepler space telescope
The Kepler space telescope has revolutionised our knowledge about exoplanets
and stars and is continuing to do so in the K2 mission. The exquisite
photometric precision, together with the long, uninterrupted observations
opened up a new way to investigate the structure and evolution of stars.
Asteroseismology, the study of stellar oscillations, allowed us to investigate
solar-like stars and to peer into the insides of red giants and massive stars.
But many discoveries have been made about classical variable stars too, ranging
from pulsators like Cepheids and RR Lyraes to eclipsing binary stars and
cataclysmic variables, and even supernovae. In this review, which is far from
an exhaustive summary of all results obtained with Kepler, we collected some of
the most interesting discoveries, and ponder on the role for amateur observers
in this golden era of stellar astrophysics.Comment: 12 pages, 6 figures, published in the Journal of the AAVSO:
https://www.aavso.org/apps/jaavso/article/3235/, v2: fixed a bad a reference.
arXiv admin note: text overlap with arXiv:1108.3083 by other author
Shockwave Behaviour in RR Lyrae Stars
Here we present the detailed analysis of some modulated Kepler and K2 RR
Lyrae stars that show peculiar bump progression in respect to the pulsation
phase.Comment: 3 pages, 3 figures, to be published in the proceedings of "The RR
Lyrae 2017 Conference", Niepolomice, Poland, 17-21 September 201
RR Lyrae stars as seen by the Kepler space telescope
The unprecedented photometric precision along with the quasi-continuous
sampling provided by the Kepler space telescope revealed new and unpredicted
phenomena that reformed and invigorated RR Lyrae star research. The discovery
of period doubling and the wealth of low-amplitude modes enlightened the
complexity of the pulsation behavior and guided us towards nonlinear and
nonradial studies. Searching and providing theoretical explanation for these
newly found phenomena became a central question, as well as understanding their
connection to the oldest enigma of RR Lyrae stars, the Blazhko effect. We
attempt to summarize the highest impact RR Lyrae results based on or inspired
by the data of the Kepler space telescope both from the nominal and the K2
missions. Besides the three most intriguing topics, the period doubling, the
low-amplitude modes, and the Blazhko effect, we also discuss the challenges of
Kepler photometry that played a crucial role in the results. The secrets of
these amazing variables, uncovered by Kepler, keep the theoretical,
ground-based and space-based research inspired in the post-Kepler era, since
light variation of RR Lyrae stars is still not completely understood.Comment: 25 pages, 9 figures, review article, accepted in Frontiers in
Astronomy and Space Science
A lupus nephritis kezelésének irányelvei, valamint a mycofenolat mofetil hatékonyságának bemutatása intézetünk lupus nephritises betegeinek körében | Clinical guideline for the treatment of lupus nephritis and single-centre results of mycofenolate mofetil among patients with lupus nephritis in the National Institute of Rheumatology and Physiotherapy, Budapest
Absztrakt
A szerzők közleményükben a lupus nephritis kezelésének legújabb irányelvei
mellett bemutatják saját mycofenolat mofetillel szerzett tapasztalataikat a
betegsĂ©g kezelĂ©sĂ©ben. A lupus nephritis Ă©s fĹ‘leg a proliferatĂv formája olyan
gyakori és komoly manifesztációja a szisztémás lupus erythematosusnak, amely
végstádiumú veseelégtelenséghez vagy akár halálhoz is vezethet. Az elmúlt
évtizedekben a lupus nephritis kezelése sokat fejlődött, ma már a kedvezőbb
mellĂ©khatás-profilĂş mycofenolat mofetil a cyclophosphamid alternatĂvájává vált a
III-as és IV-es osztályú glomerulonephritis indukciós és fenntartó kezelésében.
Lupus nephritis diagnózissal eddig 25 betegüknek kértek egyedi méltányosság
alapján támogatást mycofenolat mofetil adására. Szövettanilag legtöbben a WHO
III (A/C) és IV (A) szövettani osztályába tartoztak (30-30%), beszűkült
vesefunkciĂł csak 16%-ukban volt jelen. GlĂĽkokortikoid Ă©s cyclophosphamid
indukciós kezelés után adott mycofenolatterápia mellett az átlagos napi
proteinuria 3,18 g/napról 1,06 g/napra csökkent. A betegek 24%-ánál jött létre
komplett, 48%-ánál részleges remisszió. Ezek alapján a mycofenolat mofetil
hatĂ©kony kezelĂ©snek tarthatĂł a proliferatĂv lupus nephritis kezelĂ©sĂ©ben. Orv.
Hetil., 2016, 157(35), 1385–1393.
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Abstract
The authors present the latest guideline for the treatment of lupus nephritis and
their own single-centre results with mycofenolate mofetil treated lupus
nephritis. Lupus nephritis and mainly its proliferative form is a frequent and
potentially life-threatening manifestation of systemic lupus erythematosus that
can lead to end-stage renal disease. The treatment of lupus nephritis greatly
improved in the last decades; mycofenolate mofetil has become an alternative of
cyclophosphamide both in remission induction and as a maintenance regimen as
well in the treatment of Class III and IV glomerulonephritis. The authors
ordered mycofenolate mofetil for 25 patients with lupus nephritis so far.
Histologically most of them had Class III (A/C) or IV (A) glomerulonephritis
(30–30%), and only 16% of the patients had renal impairment at that time.
Mycofenolate mofetil given after glucocorticoid and cyclophosphamide induction
therapy reduced the daily proteinuria from 3.18 grs to 1.06 grs. Complete
remission could be achieved in 24% and partial remission in 48% of the patients.
The authors conclude that mycofenolate mofetil is effective in the therapy of
lupus nephritis. Orv. Hetil., 2016, 157(35), 1385–1393
Stress tolerance in auxin heterotrophic and autotrophic tobacco tissue cultures
The natures of the stress tolerance of auxin autotrophic and heterotrophic tobacco calli were compared. SO mM NaCI did not inhibit the growth of auxin autotrophic calli and they exhibited a lower level of peroxidase secretion into the media than that of heterotrophic cultures. The ascorbate peroxidase and catalase activities of these lines did not decrease in the presence of stressors. In the second half of the culturing period, the auxin autotrophic tissues expressed a higher GST activity than that of the heterotrophic lines
Automated Extended Aperture Photometry for K2 RR Lyrae stars
Light curves for RR Lyrae stars can be difficult to obtain properly in the K2
mission due to the similarities between the timescales of the observed physical
phenomena and the instrumental signals appearing in the data. We developed a
new photometric method called Extended Aperture Photometry (EAP), a key element
of which is to extend the aperture to an optimal size to compensate for the
motion of the telescope and to collect all available flux from the star before
applying further corrections. We determined the extended apertures for
individual stars by hand so far. Now we managed to automate the pipeline that
we intend to use for the nearly four thousand RR Lyrae targets observed in the
K2 mission. We present the outline of our pipeline and make some comparisons to
other photometric solutions.Comment: To appear in Astronomical Society of the Pacific Conference Series,
Volume 529, "RRLyrae/Cepheid2019: Frontiers of Classical Pulsators: Theory
and Observations", Cloudcroft, NM, USA October 13-18, 201
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