Photoionization modeling of the Galactic planetary nebulae Abell 39 and NGC 7027

We estimate distances to the spherical planetary nebula Abell 39 and the bipolar planetary nebula NGC 7027 by interpolating from a wide grid of photoionization models using the 3-D code, MOCASSIN. We find preliminary distances of 1.5 kpc and 0.9 kpc respectively, with uncertainties of about 30%.Comment: 2 pages, 1 figure, presented at the IAU Symposium 283 "Planetary Nebulae: an Eye to the Future", Puerto de la Cruz, Tenerife, Spain, 201

Dynamic Critical Behavior of the Chayes-Machta Algorithm for the Random-Cluster Model. I. Two Dimensions

We study, via Monte Carlo simulation, the dynamic critical behavior of the Chayes-Machta dynamics for the Fortuin-Kasteleyn random-cluster model, which generalizes the Swendsen-Wang dynamics for the q-state Potts ferromagnet to non-integer q \ge 1. We consider spatial dimension d=2 and 1.25 \le q \le 4 in steps of 0.25, on lattices up to 1024^2, and obtain estimates for the dynamic critical exponent z_{CM}. We present evidence that when 1 \le q \lesssim 1.95 the Ossola-Sokal conjecture z_{CM} \ge \beta/\nu is violated, though we also present plausible fits compatible with this conjecture. We show that the Li-Sokal bound z_{CM} \ge \alpha/\nu is close to being sharp over the entire range 1 \le q \le 4, but is probably non-sharp by a power. As a byproduct of our work, we also obtain evidence concerning the corrections to scaling in static observables.Comment: LaTeX2e, 75 pages including 26 Postscript figure

Open strings, 2D gravity and AdS/CFT correspondence

We present a detailed discussion of the duality between dilaton gravity on AdS_2 and open strings. The correspondence between the two theories is established using their symmetries and field theoretical, thermodynamic, and statistical arguments. We use the dual conformal field theory to describe two-dimensional black holes. In particular, all the semiclassical features of the black holes, including the entropy, have a natural interpretation in terms of the dual microscopic conformal dynamics. The previous results are discussed in the general framework of the Anti-de Sitter/Conformal Field Theory dualities.Comment: 22 pages, Typeset using REVTE

Numerical approximations of McKean anticipative backward stochastic differential equations arising in initial margin requirements*

We introduce a new class of anticipative backward stochastic differential equations with a dependence of McKean type on the law of the solution, that we name MKABSDE. We provide existence and uniqueness results in a general framework with relatively general regularity assumptions on the coefficients. We show how such stochastic equations arise within the modern paradigm of derivative pricing where a central counterparty (CCP) requires the members to deposit variation and initial margins to cover their exposure. In the case when the initial margin is proportional to the Conditional Value-at-Risk (CVaR) of the contract price, we apply our general result to define the price as a solution of a MKABSDE. We provide several linear and non-linear simpler approximations, which we solve using different numerical (deterministic and Monte-Carlo) methods

Heterologous Stop Codon Readthrough of Metazoan Readthrough Candidates in Yeast

Recent analysis of genomic signatures in mammals, flies, and worms indicates that functional translational stop codon readthrough is considerably more abundant in metazoa than previously recognized, but this analysis provides only limited clues about the function or mechanism of readthrough. If an mRNA known to be read through in one species is also read through in another, perhaps these questions can be studied in a simpler setting. With this end in mind, we have investigated whether some of the readthrough genes in human, fly, and worm also exhibit readthrough when expressed in S. cerevisiae. We found that readthrough was highest in a gene with a post-stop hexamer known to trigger readthrough, while other metazoan readthrough genes exhibit borderline readthrough in S. cerevisiae.National Institutes of Health (U.S.) (5U54HG004555-03

SPITZER SAGE Observations of Large Magellanic Cloud Planetary Nebulae

We present IRAC and MIPS images and photometry of a sample of previously known planetary nebulae (PNe) from the SAGE survey of the Large Magellanic Cloud (LMC) performed with the Spitzer Space Telescope. Of the 233 known PNe in the survey field, 185 objects were detected in at least two of the IRAC bands, and 161 detected in the MIPS 24 micron images. Color-color and color-magnitude diagrams are presented using several combinations of IRAC, MIPS, and 2MASS magnitudes. The location of an individual PN in the color-color diagrams is seen to depend on the relative contributions of the spectral components which include molecular hydrogen, polycyclic aromatic hydrocarbons (PAHs), infrared forbidden line emission from the ionized gas, warm dust continuum, and emission directly from the central star. The sample of LMC PNe is compared to a number of Galactic PNe and found to not significantly differ in their position in color-color space. We also explore the potential value of IR PNe luminosity functions (LFs) in the LMC. IRAC LFs appear to follow the same functional form as the well-established [O III] LFs although there are several PNe with observed IR magnitudes brighter than the cut-offs in these LFs.Comment: 18 pages, 10 figures, 3 tables, to be published in the Astronomical Journal. Additional online data available at http://www.cfa.harvard.edu/irac/publications

The role of tRNA and ribosome competition in coupling the expression of different mRNAs in Saccharomyces cerevisiae

Protein synthesis translates information from messenger RNAs into functional proteomes. Because of the finite nature of the resources required by the translational machinery, both the overall protein synthesis activity of a cell and activity on individual mRNAs are controlled by the allocation of limiting resources. Upon introduction of heterologous sequences into an organism—for example for the purposes of bioprocessing or synthetic biology—limiting resources may also become overstretched, thus negatively affecting both endogenous and heterologous gene expression. In this study, we present a mean-field model of translation in Saccharomyces cerevisiae for the investigation of two particular translational resources, namely ribosomes and aminoacylated tRNAs. We firstly use comparisons of experiments with heterologous sequences and simulations of the same conditions to calibrate our model, and then analyse the behaviour of the translational system in yeast upon introduction of different types of heterologous sequences. Our main findings are that: competition for ribosomes, rather than tRNAs, limits global translation in this organism; that tRNA aminoacylation levels exert, at most, weak control over translational activity; and that decoding speeds and codon adaptation exert strong control over local (mRNA specific) translation rates

Impact of Early Intrapatient Variability of Tacrolimus Concentrations on the Risk of Graft-Versus-Host Disease after Allogeneic Stem Cell Transplantation Using High-Dose Post-Transplant Cyclophosphamide

Tacrolimus (Tac) is a pivotal immunosuppressant agent used to prevent graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (alloHSCT). Tac is characterized by a narrow therapeutic window and a high inter-patient and intra-patient pharmacokinetic variability (IPV). Although high IPV of Tac concentrations has been associated with adverse post-transplant outcomes following solid organ transplantation, the effects of Tac IPV on alloHSCT recipients have not been determined. Tac IPV was therefore retrospectively evaluated in 128 alloHSCT recipients receiving high-dose post-transplant cyclophosphamide (PTCy) and the effects of Tac IPV on the occurrence of acute GVHD (aGVHD) were analyzed. Tac IPV was calculated from pre-dose concentrations (C0) measured during the first month after Tac initiation. The cumulative rates of grades II-IV and grades III-IV aGVHD at day +100 were 22.7% and 7%, respectively. Higher Tac IPV was associated with a greater risk of developing GVHD, with patients having IPV > 50th percentile having significantly higher rates of grades II-IV (34.9% vs. 10.8%; hazard ratio [HR] 3.858, p < 0.001) and grades III-IV (12.7% vs. 1.5%; HR 9.69, p = 0.033) aGVHD than patients having IPV ? 50th percentile. Similarly, patients with IPV > 75th percentile had higher rates of grades II-IV (41.9% vs. 16.5%; HR 3.30, p < 0.001) and grades III-IV (16.1% vs. 4.1%; HR 4.99, p = 0.012) aGVHD than patients with IPV ? 75th percentile. Multivariate analyses showed that high Tac IPV (>50th percentile) was an independent risk factor for grades II-IV (HR 2.99, p = 0.018) and grades III-IV (HR 9.12, p = 0.047) aGVHD. Determination of Tac IPV soon after alloHSCT could be useful in identifying patients at greater risk of aGVHD

MONOS: Multiplicity of Northern O-type Spectroscopic systems: I. Project description and spectral classifications and visual multiplicity of previously known objects

Context. Multiplicity in massive stars is key to understanding the chemical and dynamical evolution of galaxies. Among massive stars, those of O type play a crucial role due to their high masses and short lifetimes. Aims. MONOS (Multiplicity Of Northern O-type Spectroscopic systems) is a project designed to collect information and study O-type spectroscopic binaries with δ > −20◦ . In this first paper we describe the sample and provide spectral classifications and additional information for objects with previous spectroscopic and/or eclipsing binary orbits. In future papers we will test the validity of previous solutions and calculate new spectroscopic orbits. Methods. The spectra in this paper have two sources: the Galactic O-Star Spectroscopic Survey (GOSSS), a project that obtains blueviolet R ∼ 2500 spectroscopy of thousands of massive stars, and LiLiMaRlin, a library of libraries of high-resolution spectroscopy of massive stars obtained from four different surveys (CAFÉ-BEANS, OWN, IACOB, and NoMaDS) and additional data from our own observing programs and public archives. We have also used lucky images obtained with AstraLux. Results. We present homogeneous spectral classifications for 92 O-type spectroscopic multiple systems and ten optical companions, many of them original. We discuss the visual multiplicity of each system with the support of AstraLux images and additional sources. For eleven O-type objects and for six B-type objects we present their first GOSSS spectral classifications. For two known eclipsing binaries we detect double absorption lines (SB2) or a single moving line (SB1) for the first time, to which we add a third system reported by us recently. For two previous SB1 systems we detect their SB2 nature for the first time and give their first separate spectral classifications, something we have also done for a third object just recently identified as a SB2. We also detect nine new astrometric companions and provide updated information on several others. We emphasize the results for two stars: for σ Ori AaAbB we provide spectral classifications for the three components with a single observation for the first time thanks to a lucky spectroscopy observation obtained close to the Aa,Ab periastron and for θ 1 Ori CaCb we add it to the class of Galactic Of?p stars, raising the number of its members to six. Our sample of O-type spectroscopic binaries contains more triple- or higher-order systems than double systems.Fil: Maíz Apellániz, Jesús. Consejo Superior de Investigaciones Cientificas. Instituto Nacional de Tecnica Aeroespacial.; EspañaFil: Trigueros Páez, E.. Consejo Superior de Investigaciones Cientificas. Instituto Nacional de Tecnica Aeroespacial.; España. Universidad de Alicante; EspañaFil: Negueruela, Ignacio. Universidad de Alicante; EspañaFil: Barbá, Rodolfo. Universidad de La Serena; ChileFil: Simón Díaz, S.. Instituto Astrofisico de Canarias; España. Universidad de La Laguna; EspañaFil: Lorenzo, Javier. Universidad de Alicante; EspañaFil: Sota, Alfredo. Instituto de Astrofísica de Andalucía; EspañaFil: Gamen, Roberto Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Fariña, Cecilia. Instituto de Astrofísica de Canarias; España. Isaac Newton Group of Telescopes; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Salas, J.. Agrupación Astronómica de Huesca; EspañaFil: Caballero, Javier Alberto. Consejo Superior de Investigaciones Cientificas. Instituto Nacional de Tecnica Aeroespacial.; EspañaFil: Morrell, Nidia Irene. Las Campanas Observatory; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Pellerin, Anne. State University of New York; Estados UnidosFil: Alfaro Navarro, Emilio Javier. Instituto de Astrofísica de Andalucía; EspañaFil: Herrero, Artemio. Instituto de Astrofísica de Canarias; España. Universidad de La Laguna; EspañaFil: Arias, Julia Ines. Universidad de La Serena; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Marco, Amparo. Universidad de Alicante; Españ