15,753 research outputs found
The Milky Way Heart: Investigating molecular gas and gamma-ray morphologies in the Central Molecular Zone
Since the discovery of a broad distribution of very high energy (VHE; >0.1
TeV) gamma-rays in the Central Molecular Zone (CMZ) of the Galaxy in 2006 by
the HESS collaboration, the correlation of this emission with the integrated
intensity of the CS(1-0) molecular line emission has inferred a hadronic origin
for the gamma-rays. Here we describe the beginning of our investigation into
the strength of this correlation utilising new multi-line millimeter data from
the Mopra CMZ and HOP surveys and multi-wavelength GBT radio continuum
observations towards the CMZ and compare these in detail with the diffuse TeV
gamma-ray emission from HESS. The benefit of these new data is that they allow
us to simultaneously observe and analyse correlations using a large number
(>10) of molecular species, some of which contain their isotopologue pairs. The
use of isotopologue pairs is especially powerful, since it allows one to
analyse the optical depth of a number of different molecular species, thus
investigating the nature of the correlation over a range of different physical
conditions. Here we begin by comparing the integrated line emission and
continuum radio emission with the diffuse gamma-ray emission, and, by using
isotopologue pairs such as HCN/HCN, obtain optical depths throughout the
CMZ corresponding to regions of both strong and weak gamma-ray emission. We
find that the radio continuum better matches the peak of the gamma-ray
emission, which corresponds to the more compact -- compared to the relatively
coarse resolution of the gamma-ray images -- sources in the CMZ. Using the
isotopologue pairs, we find that the optical depth at all positions and
velocities within the CMZ are about 2--4. This is similar to that found for the
CS(1--0) line and would underestimate the mass of the CMZ, potentially
explaining why molecular line emission peaks appear offset from the gamma-ray
peaks.Comment: 8 pages, 5 figures. Accepted to the Proceedings of the 25th Texas
Symposium on Relativistic Astrophysics (Heidelberg, 2010
Using a fuzzy inference system to control a pumped storage hydro plant
The paper discusses the development of a fuzzy inference system (FIS) based governor control for a pumped storage hydroelectric plant. The First Hydro Company's plant at Dinorwig in North Wales is the largest of its kind in Europe and is mainly used for frequency control of the UK electrical grid. In previous investigations, a detailed model of the plant was developed using MATLAB(R)/SIMULINK(R) and this is now being used to compare FIS governor operation with the proportional-integral-derivative (PID) controller currently used. The paper describes the development of an FIS governor, and shows that its response to a step increase in load is superior to the PID under certain conditions of load. The paper proceeds to discuss the implications of these results in view of the possible practical application of an FIS governor at the Dinorwig plant
Magnetic substructure in the northern Fermi Bubble revealed by polarized WMAP emission
We report a correspondence between giant, polarized microwave structures
emerging north from the Galactic plane near the Galactic center and a number of
GeV gamma-ray features, including the eastern edge of the recently-discovered
northern Fermi Bubble. The polarized microwave features also correspond to
structures seen in the all-sky 408 MHz total intensity data, including the
Galactic center spur. The magnetic field structure revealed by the polarization
data at 23 GHz suggests that neither the emission coincident with the Bubble
edge nor the Galactic center spur are likely to be features of the local ISM.
On the basis of the observed morphological correspondences, similar inferred
spectra, and the similar energetics of all sources, we suggest a direct
connection between the Galactic center spur and the northern Fermi Bubble.Comment: Accepted for publication in The Astrophysical Journal Letters after
minor change
Developing Communication and Organization Skills: The ELITE Life Skills Reflective Practice Intervention
The aim of the current study was to evaluate the ELITE intervention as a method of increasing the perceived use of communication and organization skills in young people. The participants were three male field hockey players and two female tennis players from a British university. We used a series of single subject, multiple baselines, with minimal meaningful harm and benefit criteria and SMDall effect sizes to evaluate the ELITE intervention. The results revealed no meaningful harm from participating in the program, and the tennis players showed meaningful benefits. SMDall effect sizes all demonstrated that the intervention had a positive effect. Post intervention interviews indicated that participants valued the targeted life skills, and the program was enjoyable. Implications of this study suggest that scholars and practitioners can use the ELITE intervention to increase life skills in young people
The Clustering Of Galaxies Around Radio-Loud AGNs
We examine the hypothesis that mergers and close encounters between galaxies
can fuel AGNs by increasing the rate at which gas accretes towards the central
black hole. We compare the clustering of galaxies around radio-loud AGNs with
the clustering around a population of radio-quiet galaxies with similar masses,
colors and luminosities. Our catalog contains 2178 elliptical radio galaxies
with flux densities greater than 2.8 mJy at 1.4 GHz from the 6dFGS survey. We
find that radio AGNs with more than 200 times the median radio power have, on
average, more close (r<160 kpc) companions than their radio-quiet counterparts,
suggestive that mergers play a role in forming the most powerful radio
galaxies. For ellipticals of fixed stellar mass, the radio power is not a
function of large-scale environment nor halo mass, consistent with the radio
powers of ellipticals varying by orders of magnitude over billions of years.Comment: 12 pages, 6 figure
Search for exoplanets around pulsating stars of A--F type in Kepler Short Cadence data and the case of KIC 8197761
We searched for extrasolar planets around pulsating stars by examining
data for transit-like events hidden in the intrinsic
variability. All Short Cadence observations for targets with 6000 K 8500 K were visually inspected for transit-like events following the
removal of pulsational signals by sinusoidal fits. Clear transit-like events
were detected in KIC 5613330 and KIC 8197761. KIC 5613330 is a confirmed
exoplanet host (Kepler-635b), where the transit period determined here is
consistent with the literature value. KIC 8197761 is a Doradus -
Scuti star exhibiting eclipses/transits occurring every 9.8686667(27)
d, having durations of 8.37 h, and causing brightness drops . The star's pulsation spectrum contains several mode doublets
and triplets, identified as , with a mean spacing of 0.001659(15) c/d,
implying an internal rotation period of d. Trials to calculate the
size of the light travel time effect (LTTE) from the pulsations to constrain
the companion's mass ended inconclusive. Finding planets around
Doradus stars from the pulsational LTTE, therefore, is concluded to be
unrealistic. Spectroscopic monitoring of KIC 8197761 revealed sinusoidal radial
velocity variations with a semi-amplitude of km/s, while
individual spectra present rotational broadening consistent with km/s. This suggests that the stellar surface rotation is synchronized
with the orbit, whereas the stellar core rotates 30 times slower.
Combining the observed radial velocity variability with the transit photometry,
constrains the companion's mass to be M, ruling out an
exoplanet hypothesis.Comment: 12 pages, 9 figures, accepted for publication in MNRA
Wild at Heart:-The Particle Astrophysics of the Galactic Centre
We treat of the high-energy astrophysics of the inner ~200 pc of the Galaxy.
Our modelling of this region shows that the supernovae exploding here every few
thousand years inject enough power to i) sustain the steady-state, in situ
population of cosmic rays (CRs) required to generate the region's non-thermal
radio and TeV {\gamma}-ray emis-sion; ii) drive a powerful wind that advects
non-thermal particles out of the inner GC; iii) supply the low-energy CRs whose
Coulombic collisions sustain the temperature and ionization rate of the
anomalously warm, envelope H2 detected throughout the Cen-tral Molecular Zone;
iv) accelerate the primary electrons which provide the extended, non-thermal
radio emission seen over ~150 pc scales above and below the plane (the Galactic
centre lobe); and v) accelerate the primary protons and heavier ions which,
advected to very large scales (up to ~10 kpc), generate the recently-identified
WMAP haze and corresponding Fermi haze/bubbles. Our modelling bounds the
average magnetic field amplitude in the inner few degrees of the Galaxy to the
range 60 < B/microG < 400 (at 2 sigma confidence) and shows that even TeV CRs
likely do not have time to penetrate into the cores of the region's dense
molecular clouds before the wind removes them from the region. This latter
finding apparently disfavours scenarios in which CRs - in this star-burst-like
environment - act to substantially modify the conditions of star-formation. We
speculate that the wind we identify plays a crucial role in advecting
low-energy positrons from the Galactic nucleus into the bulge, thereby
explaining the extended morphology of the 511 keV line emission. (abridged)Comment: One figure corrected. Accepted for publication in MNRAS. 29 pages, 14
figure
Regulation of peripheral inflammation by spinal p38 MAP kinase in rats.
BackgroundSomatic afferent input to the spinal cord from a peripheral inflammatory site can modulate the peripheral response. However, the intracellular signaling mechanisms in the spinal cord that regulate this linkage have not been defined. Previous studies suggest spinal cord p38 mitogen-activated protein (MAP) kinase and cytokines participate in nociceptive behavior. We therefore determined whether these pathways also regulate peripheral inflammation in rat adjuvant arthritis, which is a model of rheumatoid arthritis.Methods and findingsSelective blockade of spinal cord p38 MAP kinase by administering the p38 inhibitor SB203580 via intrathecal (IT) catheters in rats with adjuvant arthritis markedly suppressed paw swelling, inhibited synovial inflammation, and decreased radiographic evidence of joint destruction. The same dose of SB203580 delivered systemically had no effect, indicating that the effect was mediated by local concentrations in the neural compartment. Evaluation of articular gene expression by quantitative real-time PCR showed that spinal p38 inhibition markedly decreased synovial interleukin-1 and -6 and matrix metalloproteinase (MMP3) gene expression. Activation of p38 required tumor necrosis factor alpha (TNFalpha) in the nervous system because IT etanercept (a TNF inhibitor) given during adjuvant arthritis blocked spinal p38 phosphorylation and reduced clinical signs of adjuvant arthritis.ConclusionsThese data suggest that peripheral inflammation is sensed by the central nervous system (CNS), which subsequently activates stress-induced kinases in the spinal cord via a TNFalpha-dependent mechanism. Intracellular p38 MAP kinase signaling processes this information and profoundly modulates somatic inflammatory responses. Characterization of this mechanism could have clinical and basic research implications by supporting development of new treatments for arthritis and clarifying how the CNS regulates peripheral immune responses
HD 2685 b: a hot Jupiter orbiting an early F-type star detected by TESS
We report on the confirmation of a transiting giant planet around the relatively hot (T_(eff) = 6801 ± 76 K) star HD 2685, whose transit signal was detected in Sector 1 data of NASA’s TESS mission. We confirmed the planetary nature of the transit signal using Doppler velocimetric measurements with CHIRON, CORALIE, and FEROS, as well as using photometric data obtained with the Chilean-Hungarian Automated Telescope and the Las Cumbres Observatory. From the joint analysis of photometry and radial velocities, we derived the following parameters for HD 2685 b: P = 4.12688_(−0.00004)^(+0.00005) days, e= 0.091_(−0.047)^(+0.039), M_P = 1.17 ± 0.12 M_J, and RP =1.44 ± 0.05 RJ. This system is a typical example of an inflated transiting hot Jupiter in a low-eccentricity orbit. Based on the apparent visual magnitude (V = 9.6 mag) of the host star, this is one of the brightest known stars hosting a transiting hot Jupiter, and it is a good example of the upcoming systems that will be detected by TESS during the two-year primary mission. This is also an excellent target for future ground- and space-based atmospheric characterization as well as a good candidate for measuring the projected spin-orbit misalignment angle through the Rossiter–McLaughlin effect
- …