1,700 research outputs found
Diffuse Ionized Gas in the Milky Way Disk
We analyze the diffuse ionized gas (DIG) in the first Galactic quadrant from
l=18deg to 40deg using radio recombination line (RRL) data from the Green Bank
Telescope. These data allow us to distinguish DIG emission from HII region
emission and thus study the diffuse gas essentially unaffected by confusion
from discrete sources. We find that the DIG has two dominant velocity
components, one centered around 100km/s associated with the luminous HII region
W43, and the other centered around 45km/s not associated with any large HII
region. Our analysis suggests that the two velocity components near W43 may be
caused by non-circular streaming motions originating near the end of the
Galactic bar. At lower Galactic longitudes, the two velocities may instead
arise from gas at two distinct distances from the Sun, with the most likely
distances being ~6kpc for the 100km/s component and ~12kpc for the 45km/s
component. We show that the intensity of diffuse Spitzer GLIMPSE 8.0um emission
caused by excitation of polyaromatic hydrocarbons (PAHs) is correlated with
both the locations of discrete HII regions and the intensity of the RRL
emission from the DIG. This implies that the soft ultra-violet photons
responsible for creating the infrared emission have a similar origin as the
harder ultra-violet photons required for the RRL emission. The 8.0um emission
increases with RRL intensity but flattens out for directions with the most
intense RRL emission, suggesting that PAHs are partially destroyed by the
energetic radiation field at these locations.Comment: Accepted for publication in ApJ (16 pages, 11 figures, 2 tables
HII Region Ionization of the Interstellar Medium: A Case Study of NGC 7538
Using data from the Green Bank Telescope, we analyze the radio continuum
(free-free) and radio recombination line (RRL) emission of the compact HII
region NGC 7538 (Sharpless 158). We detect extended radio continuum and
hydrogen RRL emission beyond the photodissociation region (PDR) toward the
north and east, but a sharp decrease in emission toward the south and west.
This indicates that a non-uniform PDR morphology is affecting the amount of
radiation "leaking" through the PDR. The strongest carbon RRL emission is found
in the western PDR that appears to be dense. We compute a leaking fraction % of the radio continuum emission measured in the plane of the sky
which represents a lower limit when accounting for the three-dimensional
geometry of the region. We detect an average
abundance ratio by number of inside the HII region and a
decrease in this ratio with increasing distance from the region beyond the PDR.
Using Herschel Space Observatory data, we show that small dust temperature
enhancements to the north and east of NGC 7538 coincide with extended radio
emission, but that the dust temperature enhancements are mostly contained
within a second PDR to the east. Unlike the giant HII region W43, the radiation
leaking from NGC 7538 seems to only affect the local ambient medium. This
suggests that giant HII regions may have a large effect in maintaining the
ionization of the interstellar medium.Comment: Accepted for publication in ApJ (15 pages, 10 figures, 2 tables
Diffuse Ionized Gas in the Milky Way Disk
We analyze the diffuse ionized gas (DIG) in the first Galactic quadrant from
l=18deg to 40deg using radio recombination line (RRL) data from the Green Bank
Telescope. These data allow us to distinguish DIG emission from HII region
emission and thus study the diffuse gas essentially unaffected by confusion
from discrete sources. We find that the DIG has two dominant velocity
components, one centered around 100km/s associated with the luminous HII region
W43, and the other centered around 45km/s not associated with any large HII
region. Our analysis suggests that the two velocity components near W43 may be
caused by non-circular streaming motions originating near the end of the
Galactic bar. At lower Galactic longitudes, the two velocities may instead
arise from gas at two distinct distances from the Sun, with the most likely
distances being ~6kpc for the 100km/s component and ~12kpc for the 45km/s
component. We show that the intensity of diffuse Spitzer GLIMPSE 8.0um emission
caused by excitation of polyaromatic hydrocarbons (PAHs) is correlated with
both the locations of discrete HII regions and the intensity of the RRL
emission from the DIG. This implies that the soft ultra-violet photons
responsible for creating the infrared emission have a similar origin as the
harder ultra-violet photons required for the RRL emission. The 8.0um emission
increases with RRL intensity but flattens out for directions with the most
intense RRL emission, suggesting that PAHs are partially destroyed by the
energetic radiation field at these locations.Comment: Accepted for publication in ApJ (16 pages, 11 figures, 2 tables
Continuous flow synthesis of heterocycles: A recent update on the flow synthesis of indoles
Indole derivatives are among the most useful and interesting heterocycles employed in drug discovery and medicinal chemistry. In addition, flow chemistry and flow technology are changing the synthetic paradigm in the field of modern synthesis. In this review, the role of flow technology in the preparation of indole derivatives is showcased. Selected examples have been described with the aim to provide readers with an overview on the tactics and technologies used for targeting indole scaffolds
Increased adrenal steroid secretion in response to CRF in women with hypothalamic amenorrhea
Objectie: To evaluate adrenal steroid hormone secretion in response to corticotropin-releasing factor (CRF) or to adrenocorticotropin
hormone in women with hypothalamic amenorrhea. Design: Controlled clinical study. Setting: Department of
Reproductive Medicine and Child Development, Section of Gynecology and Obstetrics, University of Pisa, Italy. Patient(s):
Fifteen women with hypothalamic amenorrhea were enrolled in the study. Eight normal cycling women were used as control
group. Interention(s): Blood samples were collected before and after an injection of ovine CRF (0.1 g/kg iv bolus) or after
synthetic ACTH (0.25 mg iv). Main outcome measure(s): Plasma levels of ACTH, 17-hydroxypregnenolone (17OHPe), progesterone
(P), dehydroepiandrosterone (DHEA), 17-hydroxyprogesterone (17OHP), cortisol (F), 11-deoxycortisol (S) and androstenedione
(A). Result(s): Basal plasma concentrations of ACTH, cortisol, 11-deoxycortisol, DHEA and 17OHPe were significantly
higher in patients than in controls, whereas plasma levels of progesterone and 17-OHP were significantly lower in patients than
in controls. In amenorrheic women the ratio of 17-OHPe/DHEA, of 17-OHPe/17-OHP and of 11-deoxycortisol/cortisol were
significantly higher than in controls, while a significant reduction in the ratio of 17-OHP/androstenedione, of 17-OHP/11-deoxycortisol
was obtained. In response to corticotropin-releasing factor test, plasma levels of ACTH, cortisol, 17-OHP, 11-deoxycortisol,
DHEA and androstenedione were significantly lower in patients than in controls. In response to adrenocorticotropin
hormone, plasma levels of 17-OHP, androstenedione and androstenedione/cortisol were significantly higher in patients than in
controls. Conclusions: Patients suffering for hypothalamic amenorrhea showed an increased activation of hypothalamus-pituitaryadrenal
(HPA) axis, as shown by the higher basal levels and by augmented adrenal hormone response to corticotropin-releasing
factor administration. These data suggest a possible derangement of adrenal androgen enzymatic pathway
Hormonal responses to water deficit in cambial tissues of Populus alba L.
Changes of the concentration of bioactive gibberellins and abscisic acid in the cambial region of white poplar (Populus alba L.) were investigated in one-year-old plants, to highlight how these phytohormone signals are modulated in response to water deficit. Plants were cultivated in pots outdoor and, at the time of maximum cambial growth (T0), irrigation was withdrawn for 8 d, inducing a mild water deficit, thus mimicking a condition that is recurrent in mediterranean climates when white poplar attains its maximum growth rate. The water deficit was suspended by resuming irrigation (Tmax), throughout a recovery period of two weeks (Trec). Cambial tissues were sampled at T0, Tmax and Trec. Significant changes of leaf and stem relative water content, leaf water potential, stomatal conductance, transpiration, carbon assimilation, stem shrinkage and leaf number were induced by soil water shortage, which also negatively affected cambium development. Nevertheless, these responses were almost fully reversed following the resumption of irrigation. Water deficit induced the accumulation of large amounts of abscisic acid in cambial tissues, but the hormone was brought back to pre-stress levels after the recovery period. With regard to bioactive gibberellins, GA1 was several fold more abundant than GA4 and reached the greatest level in the plants recovering from the water status imbalance. The possible functions of gibberellins and abscisic acid in the response of cambial tissues to water deficit are discussed in view of the known physiological roles and molecular mechanisms of action of these hormonal signals
STEM materials: a new frontier for an intelligent sustainable world
Materials are addressed as possible enablers for solutions to many global societal challenges. A foresight exercise has been conducted to identify research paths to design, with a new approach, a generation of materials which can provide multi-functionalities. These material systems have been named ???stem???, in analogy to living cells where a base of primitive units can be designed and assembled for self-reacting to external inputs. These materials will embed a concept of ???internet in things???, where their processing capacity will enable the systems to interact with the environment and express diverse functionalities. Stem materials do not exist yet, but many clues from diferent theoretical and experimental results suggest they can be developed, and because living organisms exist. This article aims at launching this new approach and promoting the structuring of a multi-disciplinary community to fll the research gaps
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