1,448 research outputs found
The 158 micron (CII) mapping of galaxies: Probing the atomic medium
Using the MPE/UCB Far-infrared Imaging Fabry-Perot Interferometer (FIFI) on the Kuiper Airborne Observatory (KAO), we have made large scale maps of (CII) in the spiral galaxies NGC 6946, NGC 891, M83 and the peculiar elliptical Cen A, thus allowing for the first time, detailed studies of the spatial distribution of the FIR line emission in external galaxies. We find that the (CII) emission comes from a mixture of components of interstellar gas. The brightest emission is associated with the nuclear regions, a second component traces the spiral arms as seen in the nearly face on spiral galaxies NGC 6946 and M83 and the largest star forming/H2 regions contained within them, and another extended component of low brightness can be detected in all of the galaxies far from the nucleus, beyond the extent of CO emission
The effects of star formation on the low-metallicity ISM: NGC4214 mapped with Herschel/PACS spectroscopy
We present Herschel/PACS spectroscopic maps of the dwarf galaxy NC4214
observed in 6 far infrared fine-structure lines: [C II] 158mu, [O III] 88mu, [O
I] 63mu, [O I] 146mu, [N II] 122mu, and [N II] 205mu. The maps are sampled to
the full telescope spatial resolution and reveal unprecedented detail on ~ 150
pc size scales. We detect [C II] emission over the whole mapped area, [O III]
being the most luminous FIR line. The ratio of [O III]/[C II] peaks at about 2
toward the sites of massive star formation, higher than ratios seen in dusty
starburst galaxies. The [C II]/CO ratios are 20 000 to 70 000 toward the 2
massive clusters, which are at least an order of magnitude larger than spiral
or dusty starbursts, and cannot be reconciled with single-slab PDR models.
Toward the 2 massive star-forming regions, we find that L[CII] is 0.5 to 0.8%
of the LTIR . All of the lines together contribute up to 2% of LTIR . These
extreme findings are a consequence of the lower metallicity and young,
massive-star formation commonly found in dwarf galaxies. These conditions
promote large-scale photodissociation into the molecular reservoir, which is
evident in the FIR line ratios. This illustrates the necessity to move to
multiphase models applicable to star-forming clusters or galaxies as a whole.Comment: Accepted for publication in the A&A Herschel Special Issu
Star Formation in M51 Triggered by Galaxy Interaction
We have mapped the inner 360'' regions of M51 in the 158micron [CII] line at
55'' spatial resolution using the Far-infrared Imaging Fabry-Perot
Interferometer (FIFI) on the Kuiper Airborne Observatory (KAO). The emission is
peaked at the nucleus, but is detectable over the entire region mapped, which
covers much of the optical disk of the galaxy. There are also two strong
secondary peaks at ~43% to 70% of the nuclear value located roughly 120'' to
the north-east, and south-west of the nucleus. These secondary peaks are at the
same distance from the nucleus as the corotation radius of the density wave
pattern. The density wave also terminates at this location, and the outlying
spiral structure is attributed to material clumping due to the interaction
between M51 and NGC5195. This orbit crowding results in cloud-cloud collisions,
stimulating star formation, that we see as enhanced [CII] line emission. The
[CII] emission at the peaks originates mainly from photodissociation regions
(PDRs) formed on the surfaces of molecular clouds that are exposed to OB
starlight, so that these [CII] peaks trace star formation peaks in M51. The
total mass of [CII] emitting photodissociated gas is ~2.6x10^{8} M_{sun}, or
about 2% of the molecular gas as estimated from its CO(1-0) line emission. At
the peak [CII] positions, the PDR gas mass to total gas mass fraction is
somewhat higher, 3-17%, and at the secondary peaks the mass fraction of the
[CII] emitting photodissociated gas can be as high as 72% of the molecular
mass.... (continued)Comment: 14 pages, 6 figures, Accepted in ApJ (for higher resolution figures
contact the author
A comparison of nanoparticullate CpG immunotherapy with and without allergens in spontaneously equine asthma-affected horses, an animal model
Introduction: New therapeutic strategies to modulate the immune response of
human and equine allergic asthma are still under extensive investigation.
Immunomodulating agents stimulating T-regulatory cells offer new treatment
options beyond conventional symptomatic treatment or specific immunotherapy
for human and equine allergic airway diseases, with the goal of a homoeostatic
T-helper cell balance. The aim of this study was to evaluate the effects of a
nebulized gelatin nanoparticle-CpG formulation (CpG-GNP) with and without
specific allergens for the treatment of spontaneous allergic equine asthma as
a model for human asthma. Methods: Twenty equine asthma-affected horses were
treated either with CpG-GNP alone or CpG-GNP with allergens. Two specific
allergens were selected for each horse based on history and an in-vitro test.
Each horse received seven administrations of the respective nebulized
composition and was examined before treatment, immediately after and 6 weeks
after the treatment course. Results: Clinical parameters such as breathing
rate, indirect interpleural measurement, arterial blood gases, amount of
tracheal mucus and percentage of neutrophils and cytokines in tracheal washes
and serum samples were evaluated. Treatment with CpG-GNP alone as well as in
combinations with relevant allergens resulted in clinical improvement of nasal
discharge, breathing rate, amount of secretion and viscosity, neutrophil
percentage and partial oxygen pressure directly after and 6 weeks after
treatment. There were no significant differences between the two treatments in
clinical parameters or local cytokine profiles in the tracheal wash fluid
(IL-10, IFN-g, and IL-17). IL-4 concentrations decreased significantly in both
groups. Conclusion: Nonspecific CpG-GNP-based immunotherapy shows potential as
a treatment for equine and possibly also human allergic asthma
Quantum suppression of shot noise in field emitters
We have analyzed the shot noise of electron emission under strong applied
electric fields within the Landauer-Buttiker scheme. In contrast to the
previous studies of vacuum-tube emitters, we show that in new generation
electron emitters, scaled down to the nanometer dimensions, shot noise much
smaller than the Schottky noise is observable. Carbon nanotube field emitters
are among possible candidates to observe the effect of shot-noise suppression
caused by quantum partitioning.Comment: 5 pages, 1 fig, minor changes, published versio
The Historical Context of Stock Settlement and Blockchain
n 1968, the U.S. stock market collapsed. 1 It did not flatline, of course, but major markets closed every Wednesday in an event now known as the \u27Wall Street Paperwork Crisis.\u27 2 This seizure was not caused by problems at the front end of a trade; brokers and dealers could easily keep up with the various client orders to buy or sell stock. Rather, the difficulties arose from back-end bottlenecks that occurred during the clearing and settlement process—the method by which a share of stock is transferred from seller to buyer. 3 This two-step process is necessary because the initial moment of contracting—the trade—is not executed on an instantaneous basis. The shares are exchanged later, thereby fulfilling the contractual commitment, via a settlement and clearing process that is often described as the \u27back-office plumbing\u27 of securities markets.
- …
