2,210 research outputs found
Cepheid Mass-loss and the Pulsation -- Evolutionary Mass Discrepancy
I investigate the discrepancy between the evolution and pulsation masses for
Cepheid variables. A number of recent works have proposed that non-canonical
mass-loss can account for the mass discrepancy. This mass-loss would be such
that a 5Mo star loses approximately 20% of its mass by arriving at the Cepheid
instability strip; a 14Mo star, none. Such findings would pose a serious
challenge to our understanding of mass-loss. I revisit these results in light
of the Padova stellar evolutionary models and find evolutionary masses are
()% greater than pulsation masses for Cepheids between 5<M/Mo<14. I
find that mild internal mixing in the main-sequence progenitor of the Cepheid
are able to account for this mass discrepancy.Comment: 15 pages, 3 figures, ApJ accepte
A phase Ib study of pertuzumab, a recombinant humanised antibody to HER2, and docetaxel in patients with advanced solid tumours
Pertuzumab represents the first in a new class of targeted therapeutics known as HER dimerisation inhibitors. We conducted a phase Ib study to determine the maximum-tolerated dose, the dose limiting toxicities (DLT), and pharmacokinetic (PK) interaction of docetaxel when administered in combination with pertuzumab. Initially, two dose levels of docetaxel (60 and 75 mg m−2) were explored in combination with a fixed dose of 1050 mg of pertuzumab; then two dose levels of docetaxel (75 and 100 mg m−2) were explored in combination following a fixed dose of 420 mg of pertuzumab with a loading dose of 840 mg. Both drugs were administered intravenously every 3 weeks. The latter dose of pertuzumab was allowed after an amendment to the original protocol when phase II data suggesting no difference in toxicity or activity between the 2 doses became available. Two patients out of two treated at docetaxel 75 mg m−2 in combination with pertuzumab 1050 mg suffered DLT (grade 3 diarrhoea and grade 4 febrile neutropaenia). Two out of five patients treated at docetaxel 100 mg m−2 in combination with pertuzumab 420 mg with a loading dose of 840 mg suffered DLT (grade 3 fatigue and grade 4 febrile neutropaenia). Stable disease was observed at four cycles in more than half of the patients treated and a confirmed radiological partial response with a >50% decline in PSA in a patient with hormone refractory prostate cancer were observed. There were no pharmacokinetic drug–drug interactions. The recommended phase II dose of this combination was docetaxel 75 mg m−2 and 420 mg pertuzumab following a loading dose of 840 mg
On the metallicity gradient of the Galactic disk
Aims: The iron abundance gradient in the Galactic stellar disk provides
fundamental constraints on the chemical evolution of this important Galaxy
component. However the spread around the mean slope is, at fixed Galactocentric
distance, larger than estimated uncertainties. Methods: To provide quantitative
constraints on these trends we adopted iron abundances for 265 classical
Cepheids (more than 50% of the currently known sample) based either on
high-resolution spectra or on photometric metallicity indices. Homogeneous
distances were estimated using near-infrared Period-Luminosity relations. The
sample covers the four disk quadrants and their Galactocentric distances range
from ~5 to ~17 kpc. Results: A linear regression over the entire sample
provides an iron gradient of -0.051+/-0.004 dex/kpc. The above slope agrees
quite well, within the errors, with previous estimates based either on Cepheids
or on open clusters covering similar Galactocentric distances. However, once we
split the sample in inner (Rg < 8 kpc) and outer disk Cepheids we found that
the slope (-0.130+/-0.015 dex/kpc) in the former region is ~3 times steeper
than the slope in the latter one (-0.042+/-0.004 dex/kpc). We found that in the
outer disk the radial distribution of metal-poor (MP, [Fe/H]<-0.02 dex) and
metal-rich (MR) Cepheids across the four disk quadrants does not show a clear
trend when moving from the innermost to the external disk regions. We also
found that the relative fractions of MP and MR Cepheids in the 1st and in the
3rd quadrant differ at 8 sigma (MP) and 15 sigma (MR) level.Comment: 6 pages, 6 figures, A&A accepte
Constraints on the Formation of the Globular Cluster IC 4499 from Multi-Wavelength Photometry
We present new multiband photometry for the Galactic globular cluster IC 4499
extending well past the main sequence turn-off in the U, B, V, R, I, and DDO51
bands. This photometry is used to determine that IC4499 has an age of 12 pm 1
Gyr and a cluster reddening of E(B-V) = 0.22 pm 0.02. Hence, IC 4499 is coeval
with the majority of Galactic GCs, in contrast to suggestions of a younger age.
The density profile of the cluster is observed to not flatten out to at least
r~800 arcsec, implying that either the tidal radius of this cluster is larger
than previously estimated, or that IC 4499 is surrounded by a halo. Unlike the
situation in some other, more massive, globular clusters, no anomalous color
spreads in the UV are detected among the red giant branch stars. The small
uncertainties in our photometry should allow the detection of such signatures
apparently associated with variations of light elements within the cluster,
suggesting that IC 4499 consists of a single stellar population.Comment: accepted to MNRA
Spotting the diffusion of New Psychoactive Substances over the Internet
Online availability and diffusion of New Psychoactive Substances (NPS)
represent an emerging threat to healthcare systems. In this work, we analyse
drugs forums, online shops, and Twitter. By mining the data from these sources,
it is possible to understand the dynamics of drugs diffusion and their
endorsement, as well as timely detecting new substances. We propose a set of
visual analytics tools to support analysts in tackling NPS spreading and
provide a better insight about drugs market and analysis
Contemporary management of atrial fibrillation: what can clinical registries tell us about stroke prevention and current therapeutic approaches?
Eliciting candidate anatomical routes for protein interactions: a scenario from endocrine physiology
Reply: Clinical outcome and prognostic factors for patients treated within a phase I study: the Royal Marsden Hospital Experience
The VMC Survey. V. First results for Classical Cepheids
The VISTA Magellanic Cloud (VMC, PI M.R. Cioni) survey is collecting deep
Ks-band time-series photometry of the pulsating variable stars hosted by the
system formed by the two Magellanic Clouds (MCs) and the "bridge" connecting
them. In this paper we present the first results for Classical Cepheids, from
the VMC observations of two fields in the Large Magellanic Cloud (LMC). The VMC
Ks-band light curves of the Cepheids are well sampled (12-epochs) and of
excellent precision. We were able to measure for the first time the Ks
magnitude of the faintest Classical Cepheids in the LMC (Ks\sim17.5 mag), which
are mostly pulsating in the First Overtone (FO) mode, and to obtain FO
Period-Luminosity (PL), Period-Wesenheit (PW), and Period-Luminosity-Color
(PLC) relations, spanning the full period range from 0.25 to 6 day. Since the
longest period Cepheid in our dataset has a variability period of 23 day, we
have complemented our sample with literature data for brighter F Cepheids. On
this basis we have built a PL relation in the Ks band that, for the first time,
includes short period pulsators, and spans the whole range from 1.6 to 100 days
in period. We also provide the first ever empirical PW and PLC relations using
the (V-Ks) color and time-series Ks photometry. The very small dispersion
(\sim0.07 mag) of these relations makes them very well suited to study the
three-dimensional (3D) geometry of the Magellanic system. The use of "direct"
(parallax- and Baade-Wesselink- based) distance measurements to both Galactic
and LMC Cepheids, allowed us to calibrate the zero points of the PL, PW, and
PLC relations obtained in this paper, and in turn to estimate an absolute
distance modulus of (m-M)0=18.46\pm0.03 for the LMC. This result is in
agreement with most of the latest literature determinations based on Classical
Cepheids.Comment: 12 pages, 7 figures: MNRAS in pres
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