70 research outputs found
Dynamical Processes in Globular Clusters
Globular clusters are among the most congested stellar systems in the
Universe. Internal dynamical evolution drives them toward states of high
central density, while simultaneously concentrating the most massive stars and
binary systems in their cores. As a result, these clusters are expected to be
sites of frequent close encounters and physical collisions between stars and
binaries, making them efficient factories for the production of interesting and
observable astrophysical exotica. I describe some elements of the competition
among stellar dynamics, stellar evolution, and other processes that control
globular cluster dynamics, with particular emphasis on pathways that may lead
to the formation of blue stragglers.Comment: Chapter 10, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G.
Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe
N-body simulations of gravitational dynamics
We describe the astrophysical and numerical basis of N-body simulations, both
of collisional stellar systems (dense star clusters and galactic centres) and
collisionless stellar dynamics (galaxies and large-scale structure). We explain
and discuss the state-of-the-art algorithms used for these quite different
regimes, attempt to give a fair critique, and point out possible directions of
future improvement and development. We briefly touch upon the history of N-body
simulations and their most important results.Comment: invited review (28 pages), to appear in European Physics Journal Plu
Bcl-2 and β1-integrin predict survival in a tissue microarray of small cell lung cancer.
INTRODUCTION: Survival in small cell lung cancer (SCLC) is limited by the development of chemoresistance. Factors associated with chemoresistance in vitro have been difficult to validate in vivo. Both Bcl-2 and β(1)-integrin have been identified as in vitro chemoresistance factors in SCLC but their importance in patients remains uncertain. Tissue microarrays (TMAs) are useful to validate biomarkers but no large TMA exists for SCLC. We designed an SCLC TMA to study potential biomarkers of prognosis and then used it to clarify the role of both Bcl-2 and β(1)-integrin in SCLC. METHODS: A TMA was constructed consisting of 184 cases of SCLC and stained for expression of Bcl-2 and β(1)-integrin. The slides were scored and the role of the proteins in survival was determined using Cox regression analysis. A meta-analysis of the role of Bcl-2 expression in SCLC prognosis was performed based on published results. RESULTS: Both proteins were expressed at high levels in the SCLC cases. For Bcl-2 (n=140), the hazard ratio for death if the staining was weak in intensity was 0.55 (0.33-0.94, P=0.03) and for β(1)-integrin (n=151) was 0.60 (0.39-0.92, P=0.02). The meta-analysis showed an overall hazard ratio for low expression of Bcl-2 of 0.91(0.74-1.09). CONCLUSIONS: Both Bcl-2 and β(1)-integrin are independent prognostic factors in SCLC in this cohort although further validation is required to confirm their importance. A TMA of SCLC cases is feasible but challenging and an important tool for biomarker validation
Minor Components of Micropapillary and Solid Subtypes in Lung Adenocarcinoma are Predictors of Lymph Node Metastasis and Poor Prognosis
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 tumoral and stromal immune microenvironment in malignant pleural mesothelioma: A comprehensive analysis reveals prognostic immune markers
Antitumor immune responses against solid malignancies correlate with improved patient survival. We conducted a comprehensive investigation of immune responses in tumor and tumor-associated stroma in epithelioid malignant pleural mesothelioma with the goal of characterizing the tumor immune microenvironment and identifying prognostic immune markers. We investigated 8 types of tumor-infiltrating immune cells within the tumor nest and tumor-associated stroma, as well as tumor expression of 5 cytokine/chemokine receptors in 230 patients. According to univariate analyses, high densities of tumoral CD4- and CD20-expressing lymphocytes were associated with better outcomes. High expression of tumor interleukin-7 (IL-7) receptor was associated with worse outcomes. According to multivariate analyses, stage and tumoral CD20 detection were independently associated with survival. Analysis of single immune cell infiltration for CD163(+) tumor-associated macrophages did not correlate with survival. However, analysis of immunologically relevant cell combinations identified that: (1) high CD163(+) tumor-associated macrophages and low CD8(+) lymphocyte infiltration had worse prognosis than other groups and (2) low CD163(+) tumor associated macrophages and high CD20(+) lymphocyte infiltration had better prognosis than other groups. Multivariate analyses demonstrated that CD163/CD8 and CD163/CD20 were independent prognostic factors of survival. With a recent increase in immunotherapy investigations and clinical trials for malignant pleural mesothelioma patients, our observations that CD20(+) B lymphocytes and tumor-associated macrophages are prognostic markers provide important information about the tumor microenvironment of malignant pleural mesothelioma
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