The Planetary Nebula Luminosity Function at the Dawn of Gaia

The [O III] 5007 Planetary Nebula Luminosity Function (PNLF) is an excellent extragalactic standard candle. In theory, the PNLF method should not work at all, since the luminosities of the brightest planetary nebulae (PNe) should be highly sensitive to the age of their host stellar population. Yet the method appears robust, as it consistently produces < 10% distances to galaxies of all Hubble types, from the earliest ellipticals to the latest-type spirals and irregulars. It is therefore uniquely suited for cross-checking the results of other techniques and finding small offsets between the Population I and Population II distance ladders. We review the calibration of the method and show that the zero points provided by Cepheids and the Tip of the Red Giant Branch are in excellent agreement. We then compare the results of the PNLF with those from Surface Brightness Fluctuation measurements, and show that, although both techniques agree in a relative sense, the latter method yields distances that are ~15% larger than those from the PNLF. We trace this discrepancy back to the calibration galaxies and argue that, due to a small systematic error associated with internal reddening, the true distance scale likely falls between the extremes of the two methods. We also demonstrate how PNLF measurements in the early-type galaxies that have hosted Type Ia supernovae can help calibrate the SN Ia maximum magnitude-rate of decline relation. Finally, we discuss how the results from space missions such as Kepler and Gaia can help our understanding of the PNLF phenomenon and improve our knowledge of the physics of local planetary nebulae.Comment: 12 pages, invited review at the conference "The Fundamental Cosmic Distance Scale: State of the Art and Gaia Perspective", to appear in Astrophysics and Space Scienc

Star clusters near and far; tracing star formation across cosmic time

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00690-x.Star clusters are fundamental units of stellar feedback and unique tracers of their host galactic properties. In this review, we will first focus on their constituents, i.e.\ detailed insight into their stellar populations and their surrounding ionised, warm, neutral, and molecular gas. We, then, move beyond the Local Group to review star cluster populations at various evolutionary stages, and in diverse galactic environmental conditions accessible in the local Universe. At high redshift, where conditions for cluster formation and evolution are more extreme, we are only able to observe the integrated light of a handful of objects that we believe will become globular clusters. We therefore discuss how numerical and analytical methods, informed by the observed properties of cluster populations in the local Universe, are used to develop sophisticated simulations potentially capable of disentangling the genetic map of galaxy formation and assembly that is carried by globular cluster populations.Peer reviewedFinal Accepted Versio

A MODEST review

We present an account of the state of the art in the fields explored by the research community invested in 'Modeling and Observing DEnse STellar systems'. For this purpose, we take as a basis the activities of the MODEST-17 conference, which was held at Charles University, Prague, in September 2017. Reviewed topics include recent advances in fundamental stellar dynamics, numerical methods for the solution of the gravitational N-body problem, formation and evolution of young and old star clusters and galactic nuclei, their elusive stellar populations, planetary systems, and exotic compact objects, with timely attention to black holes of different classes of mass and their role as sources of gravitational waves. Such a breadth of topics reflects the growing role played by collisional stellar dynamics in numerous areas of modern astrophysics. Indeed, in the next decade, many revolutionary instruments will enable the derivation of positions and velocities of individual stars in the Milky Way and its satellites and will detect signals from a range of astrophysical sources in different portions of the electromagnetic and gravitational spectrum, with an unprecedented sensitivity. On the one hand, this wealth of data will allow us to address a number of long-standing open questions in star cluster studies; on the other hand, many unexpected properties of these systems will come to light, stimulating further progress of our understanding of their formation and evolution.Comment: 42 pages; accepted for publication in 'Computational Astrophysics and Cosmology'. We are much grateful to the organisers of the MODEST-17 conference (Charles University, Prague, September 2017). We acknowledge the input provided by all MODEST-17 participants, and, more generally, by the members of the MODEST communit

The effect of alloxan diabetes mellitus on experimental cholesterol arteriosclerosis in the rabbit.

As social and medical progress have gradually emancipated mankind from many of the more acute and fatal diseases, so have the diseases associated with old and middle age come into prominence. Among these latter is arteriosclerosis - a disease which, with its sequelae, has assumed major importance as a cause of death and physical incapacity. Study of' the disease has yielded an immense amount of information but, up to the present, little understanding of its fundamental properties, and nothing of value for its prevention or cure. Any study which may elucidate the pathogenesis of arteriosclerosis is, therefore, of value; and it is to this end that the present experiment was designed.[...

Lymph node evaluation and survival after curative-intent resection of duodenal adenocarcinoma: A matched cohort study

Lymph node (LN) metastasis in patients with duodenal adenocarcinoma is associated with poor prognosis; however, the optimal extent of LN assessment and the interaction between LN assessment and adjuvant systemic therapy is poorly understood. Resected non-metastatic duodenal adenocarcinoma patients (n = 1743) were identified in the National Cancer Database (1998–2011). Logistic regression analysis identified covariates associated with LN metastasis. The influence of increasing LN cut-off points on overall survival (OS) was analysed using the log-rank test and Cox proportional hazards modelling. Adjuvant chemotherapy (AC) and surgery alone cohorts were matched (1:1) by propensity scores based on the likelihood of nodal metastasis or survival hazard on Cox modelling. OS in the matched cohort was compared by Kaplan–Meier estimates. LN metastases were present in 865 (49.6%) patients. Increasing LN assessment was associated with an increased likelihood of nodal involvement (P = 0.008). In node-negative patients, increasing LN assessment was associated with a decreased risk of death, with the largest actuarial survival differences observed for ≥15 LN (hazard ratio [HR] 0.63, 95% confidence interval [CI] 0.48–0.82, P = 0.001). In the propensity score-matched cohort of node-negative patients, AC was associated with non-significant improvements in 5-year actuarial (66.1% versus 58.7%, HR 0.79, 95% CI 0.53–1.18, P = 0.249), and did not vary by adequacy of LN counts (<15 LNs: HR 0.79, 95% CI 0.51–1.24, P = 0.305; ≥15 LNs: HR 0.90, 95% CI 0.35–2.30, P = 0.900). The extent of LN identification has prognostic significance in resected node-negative duodenal adenocarcinoma, but cannot be implicated in the selection of node-negative patients for AC. By analysis of the United States National Cancer Database:•Duodenal adenocarcinoma is a rare gastrointestinal malignancy.•Prognostically relevant lymph node cut-points are associated with survival variations in resected patients.•Adjuvant systemic therapy does not provide a survival advantage for node-negative patients with ‘inadequate’ lymph node staging

Biodegradability Enhancement of Biorefractory Organic Compounds using Oxidative Pretreatment

In symbolic software model checking, most approaches use predicates as symbolic representation of the state space, and SMT solvers for computations on the state space; BDDs are sometimes used as auxiliary data structure. The representation of software state spaces by BDDs was not yet thoroughly investigated, although BDDs are successful in hardware verification. The reason for this is that BDDs do not efficiently support all operations that are needed in software verification. In this work, we evaluate the use of a pure BDD representation of integer variable values, and focus on a particular class of programs: event-condition-action systems with limited operations. A symbolic representation using BDDs seems appropriate for this particular class of programs. We implement a program analysis based on BDDs and experimentally compare three symbolic techniques to verify reachability properties of ECA programs. The results show that BDDs are efficient, which yields the insight that BDDs could be used selectively for some variables (to be determined by a pre-analysis), even in general software model checking