1,242 research outputs found
IRAS 00450+7401 and the mid-infrared fade/burst cycle of R Coronae Borealis-type stars
We present optical and infrared imaging and spectroscopy of the R Coronae
Borealis-type (R Cor Bor) star IRAS 00450+7401. Optical spectra further confirm
its classification as a cool R Cor Bor system, having a hydrogen-deficient
carbon star spectral sub-class of HdC5 or later. Mid-infrared spectroscopy
reveals the typical ~8 um ``hump'' seen in other R Cor Bor stars and no other
features. A modern-epoch spectral energy distribution shows bright emission
from hot dust having Tdust>600 K. Historical infrared data reveal generally
cooler dust color temperatures combined with long-term fading trends, but
provide no discernible correlation between flux level and temperature.
Investigating the most mid-infrared variable R Cor Bor stars found in IRAS,
AKARI, and WISE data reveals similar fading trends, bursts that can show a
factor of up to 10 change in flux density between epochs, and blackbody-fit
dust color temperatures that span 400-1300 K. While some R Cor Bor stars such
as IRAS 00450+7401 appear to undergo fade/burst cycles in the mid-infrared,
significant gaps in temporal coverage prevent conclusively identifying any
preferred timescale for their mid-infrared variability and circumstellar dust
temperature changes.Comment: AJ accepted, 15 pages, 6 figures, 5 tables, and an appendi
The equational theories of representable residuated semigroups
We show that the equational theory of representable lower semilattice-ordered residuated semigroups is finitely based. We survey related results
Incidence and time course of everolimus-related adverse events in postmenopausal women with hormone receptor-positive advanced breast cancer: insights from BOLERO-2.
BackgroundIn the BOLERO-2 trial, everolimus (EVE), an inhibitor of mammalian target of rapamycin, demonstrated significant clinical benefit with an acceptable safety profile when administered with exemestane (EXE) in postmenopausal women with hormone receptor-positive (HR(+)) advanced breast cancer. We report on the incidence, time course, severity, and resolution of treatment-emergent adverse events (AEs) as well as incidence of dose modifications during the extended follow-up of this study.Patients and methodsPatients were randomized (2:1) to receive EVE 10 mg/day or placebo (PBO), with open-label EXE 25 mg/day (n = 724). The primary end point was progression-free survival. Secondary end points included overall survival, objective response rate, and safety. Safety evaluations included recording of AEs, laboratory values, dose interruptions/adjustments, and study drug discontinuations.ResultsThe safety population comprised 720 patients (EVE + EXE, 482; PBO + EXE, 238). The median follow-up was 18 months. Class-effect toxicities, including stomatitis, pneumonitis, and hyperglycemia, were generally of mild or moderate severity and occurred relatively early after treatment initiation (except pneumonitis); incidence tapered off thereafter. EVE dose reduction and interruption (360 and 705 events, respectively) required for AE management were independent of patient age. The median duration of dose interruption was 7 days. Discontinuation of both study drugs because of AEs was higher with EVE + EXE (9%) versus PBO + EXE (3%).ConclusionsMost EVE-associated AEs occur soon after initiation of therapy, are typically of mild or moderate severity, and are generally manageable with dose reduction and interruption. Discontinuation due to toxicity was uncommon. Understanding the time course of class-effect AEs will help inform preventive and monitoring strategies as well as patient education.Trial registration numberNCT00863655
The algebra of adjacency patterns: Rees matrix semigroups with reversion
We establish a surprisingly close relationship between universal Horn classes
of directed graphs and varieties generated by so-called adjacency semigroups
which are Rees matrix semigroups over the trivial group with the unary
operation of reversion. In particular, the lattice of subvarieties of the
variety generated by adjacency semigroups that are regular unary semigroups is
essentially the same as the lattice of universal Horn classes of reflexive
directed graphs. A number of examples follow, including a limit variety of
regular unary semigroups and finite unary semigroups with NP-hard variety
membership problems.Comment: 30 pages, 9 figure
Hunting for the New Symmetries in Calabi-Yau Jungles
It was proposed that the Calabi-Yau geometry can be intrinsically connected
with some new symmetries, some new algebras. In order to do this it has been
analyzed the graphs constructed from K3-fibre CY_d (d \geq 3) reflexive
polyhedra. The graphs can be naturally get in the frames of Universal
Calabi-Yau algebra (UCYA) and may be decode by universal way with changing of
some restrictions on the generalized Cartan matrices associated with the Dynkin
diagrams that characterize affine Kac-Moody algebras. We propose that these new
Berger graphs can be directly connected with the generalizations of Lie and
Kac-Moody algebras.Comment: 29 pages, 15 figure
Comparison of high-latitude line-of-sight ozone column density with derived ozone fields and the effects of horizontal inhomogeneity
International audienceExtensive ozone measurements were made during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II). We compare high-latitude line-of-sight (LOS) slant column ozone measurements from the NASA DC-8 to ozone simulated by forward integration of measurement-derived ozone fields constructed both with and without the assumption of horizontal homogeneity. The average bias and rms error of the simulations assuming homogeneity are relatively small (?6 and 10%, respectively) in comparison to the LOS measurements. The comparison improves significantly (?2% bias; 8% rms error) using forward integrations of three-dimensional proxy ozone fields reconstructed from potential vorticity-O3 correlations. The comparisons provide additional verification of the proxy fields and quantify the influence of large-scale ozone inhomogeneity. The spatial inhomogeneity of the atmosphere is a source of error in the retrieval of trace gas vertical profiles and column abundance from LOS measurements, as well as a complicating factor in intercomparisons that include LOS measurements at large solar zenith angles
VLT/UVES Spectroscopy of Individual Stars in Three Globular Clusters in the Fornax Dwarf Spheroidal Galaxy
We present a high resolution (R ~ 43000) abundance analysis of a total of
nine stars in three of the five globular clusters associated with the nearby
Fornax dwarf spheroidal galaxy. These three clusters (1, 2 and 3) trace the
oldest, most metal-poor stellar populations in Fornax. We determine abundances
of O, Mg, Ca, Ti, Cr, Mn, Fe, Ni, Zn, Y, Ba, La, Nd and Eu in most of these
stars, and for some stars also Mn and La. We demonstrate that classical
indirect methods (isochrone fitting and integrated spectra) of metallicity
determination lead to values of [Fe/H] which are 0.3 to 0.5 dex too high, and
that this is primarily due to the underlying reference calibration typically
used by these studies. We show that Cluster 1, with [Fe /H] = -2.5, now holds
the record for the lowest metallicity globular cluster. We also measure an
over-abundance of Eu in Cluster 3 stars that has only been previously detected
in a subgroup of stars in M15. We find that the Fornax globular cluster
properties are a global match to what is found in their Galactic counterparts;
including deep mixing abundance patterns in two stars. We conclude that at the
epoch of formation of globular clusters both the Milky Way and the Fornax dwarf
spheroidal galaxy shared the same initial conditions, presumably pre-enriched
by the same processes, with identical nucleosynthesis patterns.Comment: 16 pages, 12 figures. Accepted for publication in A&
Prognostic and therapeutic significance of carbohydrate antigen 19-9 as tumor marker in patients with pancreatic cancer
In pancreatic cancer ( PC) accurate determination of treatment response by imaging often remains difficult. Various efforts have been undertaken to investigate new factors which may serve as more appropriate surrogate parameters of treatment efficacy. This review focuses on the role of carbohydrate antigen 19- 9 ( CA 19- 9) as a prognostic tumor marker in PC and summarizes its contribution to monitoring treatment efficacy. We undertook a Medline/ PubMed literature search to identify relevant trials that had analyzed the prognostic impact of CA 19- 9 in patients treated with surgery, chemoradiotherapy and chemotherapy for PC. Additionally, relevant abstract publications from scientific meetings were included. In advanced PC, pretreatment CA 19- 9 levels have a prognostic impact regarding overall survival. Also a CA 19- 9 decline under chemotherapy can provide prognostic information for median survival. A 20% reduction of CA 19- 9 baseline levels within the first 8 weeks of chemotherapy appears to be sufficient to define a prognostic relevant subgroup of patients ('CA 19- 9 responder'). It still remains to be defined whether the CA 19- 9 response is a more reliable method for evaluating treatment efficacy compared to conventional imaging. Copyright (c) 2006 S. Karger AG, Basel
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