13,809 research outputs found
Massive galaxies with very young AGN
Gigahertz Peaked Spectrum (GPS) radio galaxies are generally thought to be
the young counterparts of classical extended radio sources and live in massive
ellipticals. GPS sources are vital for studying the early evolution of
radio-loud AGN, the trigger of their nuclear activity, and the importance of
feedback in galaxy evolution. We study the Parkes half-Jansky sample of GPS
radio galaxies of which now all host galaxies have been identified and 80% has
their redshifts determined (0.122 < z < 1.539). Analysis of the absolute
magnitudes of the GPS host galaxies show that at z > 1 they are on average a
magnitude fainter than classical 3C radio galaxies. This suggests that the AGN
in young radio galaxies have not yet much influenced the overall properties of
the host galaxy. However their restframe UV luminosities indicate that there is
a low level of excess as compared to passive evolution models.Comment: To appear in the proceedings of "Formation and Evolution of Galaxy
Bulges", IAUS 245; M. Bureau, E. Athanassoula & B. Barbuy, ed
An implicit pictorial methodology for measuring and retraining smokers' reactivity to pictures of pros and cons of smoking:development protocol
AbstractObjectivesThe last decades, there has been increased interest in the application of implicit pictorial tasks (e.g. Visual Probe Task (VPT), Approach Avoidance Task (AAT)) to target addictive behaviors. The present study reports on the development of implicit pictorial assessment and modification tasks aimed at targeting cognitive biases underlying motivational smoking-related cognitions (i.e. the pros and cons of smoking).MethodsRespondents were adult daily smokers not motivated to quit smoking within six months (NÂ =Â 33). A cross-sectional four-step approach using qualitative and quantitative strategies was utilized to identify and match pictures of pros and cons of smoking.ResultsThe study resulted in 30 pro-con picture pairs matched on valence, arousal and complexity: the picture pairs were used to develop a VPT assessment and training for attentional biases and an AAT assessment and training for approach-avoidance biases.ConclusionsThe developed measurement and training tasks will be used to explore and change cognitive biases regarding pros and cons of smoking. This may consequently influence the perceived pros and cons of smoking and yield positive effects with regard to the motivation to quit smoking
The Astrophysical Multipurpose Software Environment
We present the open source Astrophysical Multi-purpose Software Environment
(AMUSE, www.amusecode.org), a component library for performing astrophysical
simulations involving different physical domains and scales. It couples
existing codes within a Python framework based on a communication layer using
MPI. The interfaces are standardized for each domain and their implementation
based on MPI guarantees that the whole framework is well-suited for distributed
computation. It includes facilities for unit handling and data storage.
Currently it includes codes for gravitational dynamics, stellar evolution,
hydrodynamics and radiative transfer. Within each domain the interfaces to the
codes are as similar as possible. We describe the design and implementation of
AMUSE, as well as the main components and community codes currently supported
and we discuss the code interactions facilitated by the framework.
Additionally, we demonstrate how AMUSE can be used to resolve complex
astrophysical problems by presenting example applications.Comment: 23 pages, 25 figures, accepted for A&
Nuclear medium effects in -nucleus deep inelastic scattering
We study the nuclear medium effects in the weak structure functions
and in the deep inelastic neutrino/antineutrino
reactions in nuclei.
We use a theoretical model for the nuclear spectral functions which
incorporates the conventional nuclear effects, such as Fermi motion, binding
and nucleon correlations.
We also consider the pion and rho meson cloud contributions calculated from a
microscopic model for meson-nucleus self-energies. The calculations have been
performed using relativistic nuclear spectral functions which include nucleon
correlations. Our results are compared with the experimental data of NuTeV and
CDHSW.Comment: 24 pages, 14 figure
Molecular Diagnostics in the Mycosphaerella Leaf Spot Disease Complex of Banana and for Radopholus similis
Mycosphaerella leaf spots and nematodes threaten banana cultivation worldwide. The Mycosphaerella disease complex involves three related ascomycetous fungi: Mycosphaerella fijiensis, M. musicola and M. eumusae. The exact distribution of these three species and their disease epidemiology remain unclear, since their symptoms and life cycles are rather similar. Diagnosing these diseases and the respective causal agents is based on the presence of host symptoms and fungal fruiting structures, but is time consuming and not conducive to preventive management. In the present study, we developed rapid and robust species-specific diagnostic tools to detect and quantify M. fijiensis, M. musicola and M. eumusae. Conventional species-specific PCR primers were developed based on the actin gene that detected as little as 100, 1 and 10 pg/µl DNA from, respectively, M. fijiensis, M. musicola and M. eumusae. Furthermore, TaqMan real-time quantitative PCR assays that were developed based on the ß-tubulin gene detected quantities as low as 1 pg/µl DNA of each species from pure cultures and 1.6 pg/µl DNA/mg of M. fijiensis from dry leaf tissue. The efficacy of the tests was validated using naturally infected banana leaves. Similar technology has been used to develop a quantitative PCR assay for the banana burrowing nematode, Radopholus similis, which is currently being validate
The importance of systematic data collection, monitoring and evaluation of tuberculosis screening programmes of migrants arriving in low-incidence countries
Evaluation of Neural Networks to Identify Types of Activity Among Children Using Accelerometers, Global Positioning Systems and Heart Rate Monitors
GPS radio sources: new optical observations and an updated master list
* Aims. Identify optical counterparts, address uncertain identifications and
measure previously unknown redshifts of the host galaxies of candidate GPS
radio sources, and study their stellar populations. * Methods. Long slit
spectroscopy and deep optical imaging in the B, V and R bands, obtained with
the Very Large Telescope. * Results. We obtain new redshifts for B0316+161,
B0407-658, B0904+039, B1433-040, and identify the optical counterparts of
B0008-421 and B0742+103. We confirm the previous identification for B0316+161,
B0407-658, B0554-026, and B0904+039, and find that the previous identification
for B0914+114 is incorrect. Using updated published radio spectral information
we classify as non GPS the following sources: B0407-658, B0437-454, B1648+015.
The optical colors of typical GPS sources are consistent with single
instantaneous burst stellar population models but do not yield useful
information on age or metallicity. A new master list of GPS sources is
presented.Comment: 10 pages + GPS master list. Accepeted for publication by A&
Electric Dipole Moments of Light Nuclei From Chiral Effective Field Theory
We set up the framework for the calculation of electric dipole moments (EDMs)
of light nuclei using the systematic expansion provided by chiral effective
field theory (EFT). We take into account parity (P) and time-reversal (T)
violation which, at the quark-gluon level, originates from the QCD vacuum angle
and dimension-six operators capturing physics beyond the Standard Model. We
argue that EDMs of light nuclei can be expressed in terms of six low-energy
constants that appear in the P- and T-violating nuclear potential and electric
current. As examples, we calculate the EDMs of the deuteron, the triton, and
3He in leading order in the EFT expansion
Long Term Variability of SDSS Quasars
We use a sample of 3791 quasars from the Sloan Digital Sky Survey (SDSS)
Early Data Release (EDR), and compare their photometry to historic plate
material for the same set of quasars in order to study their variability
properties. The time base-line we attain this way ranges from a few months to
up to 50 years. In contrast to monitoring programs, where relatively few
quasars are photometrically measured over shorter time periods, we utilize
existing databases to extend this base-line as much as possible, at the cost of
sampling per quasar. Our method, however, can easily be extended to much larger
samples. We construct variability Structure Functions and compare these to the
literature and model functions. From our modeling we conclude that 1) quasars
are more variable toward shorter wavelengths, 2) their variability is
consistent with an exponentially decaying light-curve with a typical time-scale
of ~2 years, 3) these outbursts occur on typical time-scales of ~200 years.
With the upcoming first data release of the SDSS, a much larger quasar sample
can be used to put these conclusions on a more secure footing.Comment: 16 pages, accepted for publication in AJ, Sept issu
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