1,049 research outputs found
IceCube's In-Ice Radio Extension: Status and Results
In 2006-2010, several Radio Frequency (RF) detectors and calibration
equipment were deployed as part of the IceCube array at depths between 5 to
1400 meters in preparation for a future large scale GZK neutrino detector.
IceCube's deep holes and well-established data handling system provide a unique
opportunity for deep-ice RF detection studies at the South-Pole. We will
present verification and calibration results as well as a status-review of
ongoing analyses such as ice-properties, RF noise and reconstruction
algorithms.Comment: 4 pages, 6 figures, to appear in the proceedings of the Acoustic and
Radio EeV Neutrino detection Activities (ARENA) 2010 conferenc
Heating and cooling of the neutral ISM in the NGC4736 circumnuclear ring
The manner in which gas accretes and orbits within circumnuclear rings has
direct implications for the star formation process. In particular, gas may be
compressed and shocked at the inflow points, resulting in bursts of star
formation at these locations. Afterwards the gas and young stars move together
through the ring. In addition, star formation may occur throughout the ring, if
and when the gas reaches sufficient density to collapse under gravity. These
two scenarios for star formation in rings are often referred to as the `pearls
on a string' and `popcorn' paradigms. In this paper, we use new Herschel PACS
observations, obtained as part of the KINGFISH Open Time Key Program, along
with archival Spitzer and ground-based observations from the SINGS Legacy
project, to investigate the heating and cooling of the interstellar medium in
the nearby star-forming ring galaxy, NGC4736. By comparing spatially resolved
estimates of the stellar FUV flux available for heating, with the gas and dust
cooling derived from the FIR continuum and line emission, we show that while
star formation is indeed dominant at the inflow points in NGC 4736, additional
star formation is needed to balance the gas heating and cooling throughout the
ring. This additional component most likely arises from the general increase in
gas density in the ring over its lifetime. Our data provide strong evidence,
therefore, for a combination of the two paradigms for star formation in the
ring in NGC4736.Comment: accepted for publication in A&
A Detailed Study of the Radio--FIR Correlation in NGC6946 with Herschel-PACS/SPIRE from KINGFISH
We derive the distribution of the synchrotron spectral index across NGC6946
and investigate the correlation between the radio continuum (synchrotron) and
far-infrared (FIR) emission using the KINGFISH Herschel PACS and SPIRE data.
The radio--FIR correlation is studied as a function of star formation rate,
magnetic field strength, radiation field strength, and the total gas surface
brightness. The synchrotron emission follows both star-forming regions and the
so-called magnetic arms present in the inter-arm regions. The synchrotron
spectral index is steepest along the magnetic arms (), while
it is flat in places of giant H{\sc ii} regions and in the center of the galaxy
(). The map of provides an observational
evidence for aging and energy loss of cosmic ray electrons propagating in the
disk of the galaxy. Variations in the synchrotron--FIR correlation across the
galaxy are shown to be a function of both star formation and magnetic fields.
We find that the synchrotron emission correlates better with cold rather than
with warm dust emission, when the interstellar radiation field is the main
heating source of dust. The synchrotron--FIR correlation suggests a coupling
between the magnetic field and the gas density. NGC6946 shows a power-law
behavior between the total (turbulent) magnetic field strength B and the star
formation rate surface density with an index of
0.14\,(0.16)0.01. This indicates an efficient production of the turbulent
magnetic field with the increasing gas turbulence expected in actively star
forming regions. The scale-by-scale analysis of the synchrotron--FIR
correlation indicates that the ISM affects the propagation of old/diffused
cosmic ray electrons, resulting in a diffusion coefficient of \,cm\,s for 2.2\,GeV CREs.Comment: 23 pages, 13 figures, accepted for publication in Astronomy &
Astrophysics Journa
The Ionized Gas in Nearby Galaxies as Traced by the [NII] 122 and 205 \mu m Transitions
The [NII] 122 and 205 \mu m transitions are powerful tracers of the ionized
gas in the interstellar medium. By combining data from 21 galaxies selected
from the Herschel KINGFISH and Beyond the Peak surveys, we have compiled 141
spatially resolved regions with a typical size of ~1 kiloparsec, with
observations of both [NII] far-infrared lines. We measure [NII] 122/205 line
ratios in the ~0.6-6 range, which corresponds to electron gas densities
~1-300 cm, with a median value of =30 cm. Variations in
the electron density within individual galaxies can be as a high as a factor of
~50, frequently with strong radial gradients. We find that increases as a
function of infrared color, dust-weighted mean starlight intensity, and star
formation rate surface density (). As the intensity of the [NII]
transitions is related to the ionizing photon flux, we investigate their
reliability as tracers of the star formation rate (SFR). We derive relations
between the [NII] emission and SFR in the low-density limit and in the case of
a log-normal distribution of densities. The scatter in the correlation between
[NII] surface brightness and can be understood as a property of
the distribution. For regions with close to or higher than the
[NII] line critical densities, the low-density limit [NII]-based SFR
calibration systematically underestimates the SFR since [NII] emission is
collisionally quenched. Finally, we investigate the relation between [NII]
emission, SFR, and by comparing our observations to predictions from the
MAPPINGS-III code.Comment: 18 pages, 9 figures, accepted for publication in The Astrophysical
Journa
HIV-DNA Given with or without Intradermal Electroporation Is Safe and Highly Immunogenic in Healthy Swedish HIV-1 DNA/MVA Vaccinees: A Phase I Randomized Trial
We compared safety and immunogenicity of intradermal (ID) vaccination with and without electroporation (EP) in a phase I randomized placebo-controlled trial of an HIV-DNA prime HIV-MVA boost vaccine in healthy Swedish volunteers.HIV-DNA plasmids encoding HIV-1 genes gp160 subtypes A, B and C; Rev B; Gag A and B and RTmut B were given ID at weeks 0, 6 and 12 in a dose of 0.6 mg. Twenty-five volunteers received vaccine using a needle-free device (ZetaJet) with (n=16) or without (n=9) ID EP (Dermavax). Five volunteers were placebo recipients. Boosting with recombinant MVA-CMDR expressing HIV-1 Env, Gag, Pol of CRF01_AE (HIV-MVA) or placebo was performed at weeks 24 and 40. Nine of the vaccinees received a subtype C CN54 gp140 protein boost together with HIV-MVA.The ID/EP delivery was very well tolerated. After three HIV-DNA immunizations, no statistically significant difference was seen in the IFN-γ ELISpot response rate to Gag between HIV-DNA ID/EP recipients (5/15, 33%) and HIV-DNA ID recipients (1/7, 14%, p=0.6158). The first HIV-MVA or HIV-MVA+gp140 vaccination increased the IFN-γ ELISpot response rate to 18/19 (95%). CD4+ and/or CD8+ T cell responses to Gag or Env were demonstrable in 94% of vaccinees. A balanced CD4+ and CD8+ T cell response was noted, with 78% and 71% responders, respectively. IFN-γ and IL-2 dominated the CD4+ T cell response to Gag and Env. The CD8+ response to Gag was broader with expression of IFN-γ, IL-2, MIP-1β and/or CD107. No differences were seen between DNA vaccine groups. Binding antibodies were induced after the second HIV-MVA+/-gp140 in 93% of vaccinees to subtype C Env, with the highest titers among EP/gp140 recipients.Intradermal electroporation of HIV-DNA was well tolerated. Strong cell- and antibody-mediated immune responses were elicited by the HIV-DNA prime and HIV-MVA boosting regimen, with or without intradermal electroporation use.International Standard Randomised Controlled Trial Number (ISRCTN) 60284968
High prevalence of ECG variations and abnormalities in young and healthy TaMoVac 01 HIV vaccine trial volunteers from Tanzania
High prevalence of ECG variations and abnormalities in young and healthy TaMoVac 01 HIV vaccine trial volunteers from Tanzania
- …