76 research outputs found
Radio-to-UV monitoring of AO 0235+164 by the WEBT and Swift during the 2006--2007 outburst
The blazar AO 0235+164 was claimed to show a quasi-periodic behaviour in the
radio and optical bands. Moreover, an extra emission component contributing to
the UV and soft X-ray flux was detected, whose nature is not yet clear. A
predicted optical outburst was observed in late 2006/early 2007. We here
present the radio-to-optical WEBT light curves during the outburst, together
with UV data acquired by Swift in the same period. We found the optical
outburst to be as strong as the big outbursts of the past: starting from late
September 2006, a brightness increase of 5 mag led to the outburst peak in
February 19-21, 2007. We also observed an outburst at mm and then at cm
wavelengths, with an increasing time delay going toward lower frequencies
during the rising phase. Cross-correlation analysis indicates that the 1 mm and
37 GHz flux variations lagged behind the R-band ones by about 3 weeks and 2
months, respectively. These short time delays suggest that the corresponding
jet emitting regions are only slightly separated and/or misaligned. In
contrast, during the outburst decreasing phase the flux faded contemporaneously
at all cm wavelengths. This abrupt change in the emission behaviour may suggest
the presence of some shutdown mechanism of intrinsic or geometric nature. The
behaviour of the UV flux closely follows the optical and near-IR one. By
separating the synchrotron and extra component contributions to the UV flux, we
found that they correlate, which suggests that the two emissions have a common
origin.Comment: 9 pages, 7 figures, in press for Astronomy and Astrophysic
WEBT and XMM-Newton observations of 3C 454.3 during the post-outburst phase. Detection of the little and big blue bumps
The blazar 3C 454.3 underwent an unprecedented optical outburst in spring
2005. This was first followed by a mm and then by a cm radio outburst, which
peaked in February 2006. We report on follow-up observations by the WEBT to
study the multiwavelength emission in the post-outburst phase. XMM-Newton
observations on July and December 2006 added information on the X-ray and UV
fluxes. The source was in a faint state. The radio flux at the higher
frequencies showed a fast decreasing trend, which represents the tail of the
big radio outburst. It was followed by a quiescent state, common at all radio
frequencies. In contrast, moderate activity characterized the NIR and optical
light curves, with a progressive increase of the variability amplitude with
increasing wavelength. We ascribe this redder-when-brighter behaviour to the
presence of a "little blue bump" due to line emission from the broad line
region, which is clearly visible in the source SED during faint states.
Moreover, the data from the XMM-Newton OM reveal a rise of the SED in the UV,
suggesting the existence of a "big blue bump" due to thermal emission from the
accretion disc. The X-ray spectra are well fitted with a power-law model with
photoelectric absorption, possibly larger than the Galactic one. However, the
comparison with previous X-ray observations would imply that the amount of
absorbing matter is variable. Alternatively, the intrinsic X-ray spectrum
presents a curvature, which may depend on the X-ray brightness. In this case,
two scenarios are possible.Comment: 9 pages, 7 figures, accepted for publication in A&
Sähköisten terveyspalveluiden opetus lääketieteessä
Digitalisaation myötä terveydenhuollon toiminnot muuttuvat nopeasti, ja sähköiset työkalut sekä palvelut ovat jo arkipäivää. Vaikutukset näkyvät koulutustarpeena, koska terveydenhuollon ammattilaisten digiosaaminen tulee turvata. Lääkärien peruskoulutuksen tulisi sisältää etälääketiedettä ja sähköisen terveydenhuollon palveluja (e-health) koskevaa opetusta. Kansallisessa MEDigi-hankkeessa määriteltiin suomalaisen e-health-opetuksen aihealueet ja tehtiin niille ydinainesanalyysi. Työryhmän työn perusteella määräytyi kaksitoista e-health-opetukseen soveltuvaa aihealuetta lääketieteen ja hammaslääketieteen peruskoulutuksessa. Niiden sisältämien opetusaiheiden keskeisyys määriteltiin kolmiportaisesti. Tuloksia sovellettiin pilottina Oulun yliopistossa lääketieteen viidennen vuosikurssin opiskelijoille toteutettuun teemapäivään, jonka opetussisältö muokattiin vastaamaan ydinainesanalyysin tuloksia. Opetus toteutettiin koronapandemian takia kokonaan etäopetuksena. Jatkossa tavoitteena on kansallisesti integroida ydinainesanalyysiin perustuva e-health-opetus suomalaiseen lääkärikoulutukseen
Organic residue analysis shows sub-regional patterns in the use of pottery by Northern European hunter–gatherers
The introduction of pottery vessels to Europe has long been seen as closely linked with the spread of agriculture and pastoralism from the Near East. The adoption of pottery technology by hunter–gatherers in Northern and Eastern Europe does not fit this paradigm, and its role within these communities is so far unresolved. To investigate the motivations for hunter–gatherer pottery use, here, we present the systematic analysis of the contents of 528 early vessels from the Baltic Sea region, mostly dating to the late 6th–5th millennium cal BC, using molecular and isotopic characterization techniques. The results demonstrate clear sub-regional trends in the use of ceramics by hunter–gatherers; aquatic resources in the Eastern Baltic, non-ruminant animal fats in the Southeastern Baltic, and a more variable use, including ruminant animal products, in the Western Baltic, potentially including dairy. We found surprisingly little evidence for the use of ceramics for non-culinary activities, such as the production of resins. We attribute the emergence of these subregional cuisines to the diffusion of new culinary ideas afforded by the adoption of pottery, e.g. cooking and combining foods, but culturally contextualized and influenced by traditional practices
Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution
The larger number of models of asteroid shapes and their rotational states
derived by the lightcurve inversion give us better insight into both the nature
of individual objects and the whole asteroid population. With a larger
statistical sample we can study the physical properties of asteroid
populations, such as main-belt asteroids or individual asteroid families, in
more detail. Shape models can also be used in combination with other types of
observational data (IR, adaptive optics images, stellar occultations), e.g., to
determine sizes and thermal properties. We use all available photometric data
of asteroids to derive their physical models by the lightcurve inversion method
and compare the observed pole latitude distributions of all asteroids with
known convex shape models with the simulated pole latitude distributions. We
used classical dense photometric lightcurves from several sources and
sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff,
Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the
lightcurve inversion method to determine asteroid convex models and their
rotational states. We also extended a simple dynamical model for the spin
evolution of asteroids used in our previous paper. We present 119 new asteroid
models derived from combined dense and sparse-in-time photometry. We discuss
the reliability of asteroid shape models derived only from Catalina Sky Survey
data (IAU code 703) and present 20 such models. By using different values for a
scaling parameter cYORP (corresponds to the magnitude of the YORP momentum) in
the dynamical model for the spin evolution and by comparing synthetics and
observed pole-latitude distributions, we were able to constrain the typical
values of the cYORP parameter as between 0.05 and 0.6.Comment: Accepted for publication in A&A, January 15, 201
A theory of moving form perception: Synergy between masking, perceptual grouping, and motion computation in retinotopic and non-retinotopic representations
Because object and self-motion are ubiquitous in natural viewing conditions,
understanding how the human visual system achieves a relatively clear perception
for moving objects is a fundamental problem in visual perception. Several
studies have shown that the visible persistence of a briefly presented
stationary stimulus is approximately 120 ms under normal viewing conditions.
Based on this duration of visible persistence, we would expect moving objects to
appear highly blurred. However, in human vision, objects in motion typically
appear relatively sharp and clear. We suggest that clarity of form in dynamic
viewing is achieved by a synergy between masking, perceptual grouping, and
motion computation across retinotopic and non-retinotopic representations. We
also argue that dissociations observed in masking are essential to create and
maintain this synergy
The WEBT Campaign on the Intermediate BL Lac Object 3C66A in 2007-2008
Prompted by a high optical state in September 2007, the Whole Earth Blazar
Telescope (WEBT) consortium organized an intensive optical, near-IR (JHK) and
radio observing campaign on the intermediate BL Lac object 3C 66A throughout
the fall and winter of 2007 -- 2008. The source remained in a high optical
state throughout the observing period and exhibited several bright flares on
time scales of ~ 10 days. This included an exceptional outburst around
September 15 - 20, 2007, reaching a peak brightness at R ~ 13.4. Our campaign
revealed microvariability with flux changes up to |dR/dt| ~ 0.02 mag/hr. Our
observations do not reveal evidence for systematic spectral variability or
spectral lags. We infer a value of the magnetic field in the emission region of
B ~ 19 e_B^{2/7} \tau_h^{-6/7} D_1^{13/7} G. From the lack of systematic
spectral variability, we can derive an upper limit on the Doppler factor, D <=
28 \tau_h^{-1/8} e_B^{3/16}. This is in agreement with superluminal motion
measurements of \beta_{app} \le 27 and argues against models with very high
Lorentz factors of \Gamma > 50, required for a one-zone SSC interpretation of
some high-frequency-peaked BL Lac objects detected at TeV gamma-ray energies.Comment: Accepted for publication in The Astrophysical Journa
The 72-h WEBT microvariability observation of blazar S5 0716 + 714 in 2009
Context. The international Whole Earth Blazar Telescope (WEBT) consortium planned and carried out three days of intensive micro-variability observations of S5 0716 + 714 from February 22, 2009 to February 25, 2009. This object was chosen due to its bright apparent magnitude range, its high declination, and its very large duty cycle for micro-variations. Aims. We report here on the long continuous optical micro-variability light curve of 0716+714 obtained during the multi-site observing campaign during which the Blazar showed almost constant variability over a 0.5 mag range. The resulting light curve is presented here for the first time. Observations from participating observatories were corrected for instrumental differences and combined to construct the overall smoothed light curve. Methods. Thirty-six observatories in sixteen countries participated in this continuous monitoring program and twenty of them submitted data for compilation into a continuous light curve. The light curve was analyzed using several techniques including Fourier transform, Wavelet and noise analysis techniques. Those results led us to model the light curve by attributing the variations to a series of synchrotron pulses. Results. We have interpreted the observed microvariations in this extended light curve in terms of a new model consisting of individual stochastic pulses due to cells in a turbulent jet which are energized by a passing shock and cool by means of synchrotron emission. We obtained an excellent fit to the 72-hour light curve with the synchrotron pulse model. © ESO, 2013
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