52 research outputs found
NuSTAR Reveals the Comptonizing Corona of the Broad-Line Radio Galaxy 3C 382
Broad-line radio galaxies (BLRGs) are active galactic nuclei that produce
powerful, large-scale radio jets, but appear as Seyfert 1 galaxies in their
optical spectra. In the X-ray band, BLRGs also appear like Seyfert galaxies,
but with flatter spectra and weaker reflection features. One explanation for
these properties is that the X-ray continuum is diluted by emission from the
jet. Here, we present two NuSTAR observations of the BLRG 3C 382 that show
clear evidence that the continuum of this source is dominated by thermal
Comptonization, as in Seyfert 1 galaxies. The two observations were separated
by over a year and found 3C 382 in different states separated by a factor of
1.7 in flux. The lower flux spectrum has a photon-index of
, while the photon-index of the higher flux
spectrum is . Thermal and anisotropic
Comptonization models provide an excellent fit to both spectra and show that
the coronal plasma cooled from keV in the low flux data to
keV in the high flux observation. This cooling behavior is
typical of Comptonizing corona in Seyfert galaxies and is distinct from the
variations observed in jet-dominated sources. In the high flux observation,
simultaneous Swift data are leveraged to obtain a broadband spectral energy
distribution and indicates that the corona intercepts % of the optical
and ultraviolet emitting accretion disk. 3C 382 exhibits very weak reflection
features, with no detectable relativistic Fe K line, that may be best
explained by an outflowing corona combined with an ionized inner accretion
disk.Comment: 8 pages, 8 figures, accepted by Ap
A Switch in the Control of Growth of the Wing Imaginal Disks of Manduca sexta
Background: Insulin and ecdysone are the key extrinsic regulators of growth for the wing imaginal disks of insects. In vitro tissue culture studies have shown that these two growth regulators act synergistically: either factor alone stimulates only limited growth, but together they stimulate disks to grow at a rate identical to that observed in situ. It is generally thought that insulin signaling links growth to nutrition, and that starvation stops growth because it inhibits insulin secretion. At the end of larval life feeding stops but the disks continue to grow, so at that time disk growth has become uncoupled from nutrition. We sought to determine at exactly what point in development this uncoupling occurs. Methodology: Growth and cell proliferation in the wing imaginal disks and hemolymph carbohydrate concentrations were measured at various stages in the last larval instar under experimental conditions of starvation, ligation, rescue, and hormone treatment. Principal Findings: Here we show that in the last larval instar of M. sexta, the uncoupling of nutrition and growth occurs as the larva passes the critical weight. Before this time, starvation causes a decline in hemolymph glucose and trehalose and a cessation of wing imaginal disks growth, which can be rescued by injections of trehalose. After the critical weight the trehalose response to starvation disappears, and the expression of insulin becomes decoupled from nutrition. After the critical weight the wing disks loose their sensitivity to repression by juvenile hormone, and factors from the abdomen, bu
Effects of both ecdysone and the acclimation to low temperature, on growth and metabolic rate of juvenile freshwater crayfish Cherax quadricarinatus (Decapoda, Parastacidae)
Prothoracicotropic Hormone and Ecdysone Action on Moulting in the Penultimate Instar of Tobacco Cut Worm, Spodoptera litura (F.)
Basic fibroblast growth factor counteracts the suppressive effect of transforming growth factor-beta 1 on human myeloid progenitor cells
Basic fibroblast growth factor counteracts the suppressive effect of transforming growth factor-beta 1 on human myeloid progenitor cells
Role of ventral nerve cord and peripheral nerves in metamorphosis and nerve cord shortening in the lemon-butterfly, Papilio demoleus (Lepidoptera)
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