401 research outputs found
Discovery of CH and OH in the -513 km s-1 Ejecta of Eta Carinae
The very massive star, Eta Carinae, is enshrouded in an unusual complex of
stellar ejecta, which is highly depleted in C and O, and enriched in He and N.
This circumstellar gas gives rise to distinct absorption components
corresponding to at least 20 different velocities along the line-of-sight. The
velocity component at -513 kms-1 exhibits very low ionization with
predominantly neutral species of iron-peak elements. Our statistical
equilibrium/photoionization modeling indicates that the low temperature (T =
760 K) and high density (n_H=10^7 cm^-3) of the -513 kms-1 component is
conducive to molecule formation including those with the elements C and O.
Examination of echelle spectra obtained with the Space Telescope Imaging
Spectrograph (STIS) aboard the confirms the model's predictions. The molecules,
H_2, CH, and most likely OH, have been identified in the -513 kms-1 absorption
spectrum. This paper presents the analysis of the HST/STIS spectra with the
deduced column densities for CH, OH and C I, and upper limit for CO. It is
quite extraordinary to see molecular species in a cool environment at such a
high velocity. The sharp molecular and ionic absorptions in this extensively
CNO- processed material offers us a unique environment for studying the
chemistry, dust formation processes, and nucleosynthesis in the ejected layers
of a highly evolved massive star.Comment: tentatively scheduled for the ApJ 1 September 2005, v630, 1 issu
Corrigendum: Airway T cells protect against RSV infection in the absence of antibody
Correction to: Mucosal Immunology (2018) 11, 249–256; doi:10.1038/mi.2017.46; published online 24 May 201
Comparative analysis of enzymatically produced novel linear DNA constructs with plasmids for use as DNA vaccines
The use of DNA to deliver vaccine antigens offers many advantages, including ease of manufacture and cost. However, most DNA vaccines are plasmids and must be grown in bacterial culture, necessitating elements which are either unnecessary for effective gene delivery (e.g. bacterial origins of replication) or undesirable (e.g. antibiotic resistance genes). Removing these elements may improve the safety profile of DNA for the delivery of vaccines. Here we describe a novel, double-stranded, linear DNA construct produced by an enzymatic process that solely encodes an antigen expression cassette, comprising antigen, promoter, polyA tail and telomeric ends. We compared these constructs (called ‘Doggybones’ because of their shape) with conventional plasmid DNA. Using luciferase-expressing constructs, we demonstrated that expression levels were equivalent between Doggybones and plasmids both in vitro and in vivo. When mice were immunized with DNA constructs expressing the HIV envelope protein gp140, equivalent humoral and cellular responses were induced. Immunizations with either construct type expressing haemagluttinin were protective against H1N1 influenza challenge. This is the first example of an effective DNA vaccine which can be produced on a large scale by enzymatic processes
Observational evidence of spin-induced precession in active galactic nuclei
We show that it is possible to explain the physical origin of jet precession
in active galactic nuclei (AGNs) through the misalignment between the rotation
axes of the accretion disk and of the Kerr black hole. We apply this scenario
to quasars, Seyfert galaxies and also to the Galactic Center black hole Sgr A*,
for which signatures of either jet or disk precession have been found. The
formalism adopted is parameterized by the ratio of the precession period to the
black hole mass and can be used to put constraints to the physical properties
of the accretion disk as well as to the black hole spin in those systems.Comment: 10 pages, 1 figure, accepted for publication in ApJ Letter
Gravitational radiation from precessing accretion disks in gamma-ray bursts
We study the precession of accretion disks in the context of gamma-ray burst
inner engines. Our aim is to quantitatively estimate the characteristics of
gravitational waves produced by the precession of the transient accretion disk
in gamma-ray bursts. We evaluate the possible periods of disk precession caused
by the Lense-Thirring effect using an accretion disk model that allows for
neutrino cooling. Assuming jet ejection perpendicular to the disk plane and a
typical intrinsic time-dependence for the burst, we find gamma-ray light curves
that have a temporal microstructure similar to that observed in some reported
events. The parameters obtained for the precession are then used to evaluate
the production of gravitational waves. We find that the precession of accretion
disks of outer radius smaller than cm and accretion rates above 1 solar
mass per second could be detected by Advanced LIGO if they occur at distances
of less than 100 Mpc. We conclude that the precession of a neutrino-cooled
accretion disk in long gamma-ray bursts can be probed by gravitational wave
astronomy. Precession of the disks in short gamma-ray events is undetectable
with the current technology.Comment: 5 pages, 5 figures, accepted for publication in A&
Simulating nearly edge-on sloshing in the galaxy cluster Abell 2199
Off-axis collisions between galaxy clusters may induce the phenomenon of
sloshing, causing dense gas to be dragged from the cool core of a cluster,
resulting in a spiral of enhanced X-ray emission. Abell 2199 displays
signatures of sloshing in its core and it is possible that the orbital plane of
the collision is seen nearly edge-on. We aim to evaluate whether the features
of Abell 2199 can be explained by a sloshing spiral seen under a large
inclination angle. To address this, we perform tailored hydrodynamical -body
simulations of a non-frontal collision with a galaxy group of
. We obtain a suitable scenario in
which the group passed by the main cluster core 0.8 Gyr ago, with a pericentric
separation of 292 kpc. Good agreement is obtained from the temperature maps as
well as the residuals from a -model fit to the simulated X-ray emission.
We find that under an inclination of the simulation results
remain consistent with the observations.Comment: 13 pages, 14 figures, accepted for publication in MNRAS; replaced
Fig.
Comportamento da Macrofauna edáfica em diferentes modelos de arborização de cafeeiro Robusta (Coffea canephora) em Rondônia.
O levantamento da fauna edáfica do solo é uma forma indicada de avaliar a viabilidade em função do manejo deste tipo de sistema. O objetivo deste trabalho foi fazer um levantamento da ocorrência da macrofauna do solo em 05 (dez) propriedades cultivadas com o café Robusta (Coffea canephora) arborizado no município de Rolim de Moura, localizado na região da Zona da Mata/RO em duas épocas diferentes. Na época chuvosa e seca, as Ordens com maiores frequência de ocorrência foram Hymenoptera, Araneae, Coleoptera, Dermaptera, Orthoptera, Isoptera, Acari, Lithobiomorpha, Diptera, Hemiptera. Através do índice de diversidade de Shannon identificou-se propriedades com maior estabilidade, principalmente quando houve maior diversidade de espécies florestais nos SAFs. O manejo dos SAFs, o clima, a diversidade de espécies florestais e o tamanho das áreas amostradas possivelmente influenciam a diversidade de Ordens da macrofauna
Profile of a Cohort of 78 Italian Patients with Mucous Membrane Pemphigoid: Correlation Between Reactivity Profile and Clinical Involvement
Direct diagnosis of mucous membrane pemphigoid (MMP) is not easy. Circulating autoantibodies targeting bullous pemphigoid antigens of 180 kDa and 230 kDa (BP180 and BP230), \u3b16\u3b24 integrin, laminin 332 and type VII collagen (Col VII) are not always present. The aims of this study were to characterize the humoral immune response of a cohort of Italian patients with MMP, its association with clinical involvement and severity, and to design an algorithm for efficient serological diagnosis. Seventy-eight MMP sera were studied retrospectively by indirect immunofluorescence on salt-split skin, enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Indirect immunofluorescence on salt-split skin resulted in the most sensitive approach for diagnosis of MMP. BP180 was the major autoantigen in MMP patients with oral and cutaneous involvement. Significant associations were found between BP180 reactivity and oral and cutaneous localization of the lesions (p\u2009=\u20090.006), and between Col VII positivity and Setterfield severity score (p\u2009=\u20090.020)
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