Maximum likelihood method for fitting the Fundamental Plane of the 6dF Galaxy Survey

We have used over 10,000 early-type galaxies from the 6dF Galaxy Survey (6dFGS) to construct the Fundamental Plane across the optical and near-infrared passbands. We demonstrate that a maximum likelihood fit to a multivariate Gaussian model for the distribution of galaxies in size, surface brightness and velocity dispersion can properly account for selection effects, censoring and observational errors, leading to precise and unbiased parameters for the Fundamental Plane and its intrinsic scatter. This method allows an accurate and robust determination of the dependencies of the Fundamental Plane on variations in the stellar populations and environment of early-type galaxies.Comment: 3 pages, 1 figure, to appear in the proceedings of the IAU Symposium 262 "Stellar Populations: Planning for the Next Decade", Charlot and Bruzual ed

Calcitonin receptor gene expression in K562 chronic myelogenous leukemic cells

BACKGROUND: The peptide hormone calcitonin (CT) can significantly effect the proliferation rate of CT receptor (CTR) positive human cancer cells. We wish to identify additional human cancers expressing CTRs and assay the effects of CT on their growth rates and signal transduction pathways. RESULTS: The expression of the human calcitonin receptor (hCTR) gene in the chronic myelogenous leukemia cell line K562 was examined. RT-PCR on total RNA extracted from K562 cells detected the presence of hCTR mRNA. Further analysis demonstrated that multiple hCTR isoforms were present. Incubation of K562 cells with salmon calcitonin (sCT), but not amylin, caused an increase in intracellular levels of cAMP similar to that induced by forskolin treatment. We further demonstrated that butyrate induced erythroid differentiation of K562 cells caused a significant decrease in hCTR mRNA levels. However, phorbol myristate acetate (PMA) induced megakaryocytic differentiation of these cells had no significant effect on hCTR mRNA levels. We demonstrated that exposure to various concentrations of sCT had no effect on the cellular proliferation of K562 cells in vitro. CONCLUSION: Chronic myelogenous k562 cells express multiple CTR isoforms. However, CT does not effect K562 proliferation rates. It is likely that the small increase in intracellular levels of cAMP following CT treatment is not sufficient to interfere with cellular growth

Inhibiting CDK4/6 in pancreatic ductal adenocarcinoma via microRNA-21

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies, with a 5-year survival rate of 5–10 %. The high mortality rate is due to the asymptomatic progression of clinical features in metastatic stages of the disease, which renders standard therapeutic options futile. PDAC is characterised by alterations in several genes that drive carcinogenesis and limit therapeutic response. The two most common genetic aberrations in PDAC are the mutational activation of KRAS and loss of the tumour suppressor CDK inhibitor 2A (CDKN2A), which culminate the activation of the cyclin-dependent kinase 4 and 6 (CDK4/6), that promote G1 cell cycle progression. Therapeutic strategies focusing on the CDK4/6 inhibitors such as palbociclib (PD-0332991) may potentially improve outcomes in this malignancy. MicroRNAs (miRs/miRNAs) are small endogenous non-coding RNA molecules associated with cellular proliferation, invasion, apoptosis, and cell cycle. Primarily, miR-21 promotes cell proliferation and a higher proportion of PDAC cells in the S phase, while knockdown of miR-21 has been linked to cell cycle arrest at the G2/M phase and inhibition of cell proliferation. In this study, using a CRISPR/Cas9 loss-of-function screen, we individually silenced the expression of miR-21 in two PDAC cell lines and in combination with PD-0332991 treatment, we examined the synergetic mechanisms of CDK4/6 inhibitors and miR-21 knockouts (KOs) on cell survival and death. This combination reduced cell proliferation, cell viability, increased apoptosis and G1 arrest in vitro. We further analysed the mitochondrial respiration and glycolysis of PDAC cells; then assessed the protein content of these cells and revealed numerous Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with PD-0332991 treatment and miR-21 knocking out. Our results demonstrate that combined targeting of CDK4/6 and silencing of miR-21 represents a novel therapeutic strategy in PDAC

Improved Blast Capacity of Pre-engineered Metal Buildings using Coupled CFD and FEA Modeling

PresentationThe initial CCPS guideline [CCPS, 1996] for estimating lethality for building occupants within petrochemical buildings subjected to blast hazards was based on building construction type and peak overpressure. This method allows for a quick screening of building occupant vulnerability but does not include the effects of the duration of the blast that the buildings are subjected to. Blast hazards within petrochemical facilities include vapor cloud explosions (VCE), BLEVEs, and bursting pressure vessels. VCE’s include both deflagrations having long blast durations and detonations having much shorter durations. Bursting pressure vessels can also be characterized as having relatively short durations. Therefore, the latest CCPS guideline [CCPS, 2012] removed this singular peak overpressure methodology and provided occupant vulnerability as a function of building damage and construction type as a function of peak overpressure and duration. Unfortunately, this improved method on blast characterization did not provide a way to correlate blast loading with building damage. This blast-to-damage correlation is required to conduct quantitative risk assessments. A range of simplified tools are available for assessing the response of structural components and building construction types to blast loads. These tools include Single Degree of Freedom (SDOF) models and Pressure-Impulse (P-I) iso-damage charts. These simplified tools generally do not account for the complex response and failure of real structures or the difference in response to different forms of blast loading that include finite rise times (blast waves). Iso-damage charts may be based upon historical data gathered from a range of sources and are often based upon blast damage caused by High Explosive (HE) detonations. This presentation illustrates the use of multi-degree of freedom structural systems for a pre- engineered metal building (PEMB). PEMBs represent the majority of building construction within petrochemical facilities. Computational Structural Dynamic (CSD) finite element analysis (FEA) and Computational Fluid Dynamic (CFD) approaches are used to show the level of conservatism in estimating the blast capacity of PEMBs compared to more traditional SDOF methods. Fully coupled CFD and FEA modeling that includes the beneficial effect of including the air that is internal to the building is demonstrated

Cosmological Model Predictions for Weak Lensing: Linear and Nonlinear Regimes

Weak lensing by large scale structure induces correlated ellipticities in the images of distant galaxies. The two-point correlation is determined by the matter power spectrum along the line of sight. We use the fully nonlinear evolution of the power spectrum to compute the predicted ellipticity correlation. We present results for different measures of the second moment for angular scales \theta \simeq 1'-3 degrees and for alternative normalizations of the power spectrum, in order to explore the best strategy for constraining the cosmological parameters. Normalizing to observed cluster abundance the rms amplitude of ellipticity within a 15' radius is \simeq 0.01 z_s^{0.6}, almost independent of the cosmological model, with z_s being the median redshift of background galaxies. Nonlinear effects in the evolution of the power spectrum significantly enhance the ellipticity for \theta < 10' -- on 1' the rms ellipticity is \simeq 0.05, which is nearly twice the linear prediction. This enhancement means that the signal to noise for the ellipticity is only weakly increasing with angle for 2'< \theta < 2 degrees, unlike the expectation from linear theory that it is strongly peaked on degree scales. The scaling with cosmological parameters also changes due to nonlinear effects. By measuring the correlations on small (nonlinear) and large (linear) angular scales, different cosmological parameters can be independently constrained to obtain a model independent estimate of both power spectrum amplitude and matter density \Omega_m. Nonlinear effects also modify the probability distribution of the ellipticity. Using second order perturbation theory we find that over most of the range of interest there are significant deviations from a normal distribution.Comment: 38 pages, 11 figures included. Extended discussion of observational prospects, matches accepted version to appear in Ap

A rich, nearby galaxy cluster in Sagittarius

We report on the existence of a rich, heavily obscured galaxy cluster (or a set of clusters) in Sagittarius, centered near l_(II) ≃ 359°, b_(II) ≃ 8°. About 30 objects, originally identified by Terzan and his collaborators, were imaged and followed up spectroscopically. We present here redshifts for 21 galaxies found among them. There is a pronounced concentration at cz ≃ 8600 km/s (containing 14 out of the 21 galaxies), and another possible concentration near cz ≃ 11 340 km/s (five out of 21). This putative Sagittarius cluster is probably part of a larger system, involving the Ophiuchus cluster at l_(II) ≃ 1°, b_(II) ≃ 9°, cz ≃ 8400 km/s, previously identified by Johnston et al. and Wakamatsu and Malkan. The heavy extinction on this line of sight (we estimate A_v ~ 5^m from the observed Balmer decrements) suggests that there is a much larger, as yet undetected number of galaxies in this direction. We propose that the Sagittarius-Ophiuchus concentration may be a massive cluster, or even a supercluster, comparable in richness to the Coma-A 1367 system, and at a comparable distance. The existence of this concentration serves as a reminder that some possibly dynamically important constituents of the local large-scale structure may be absent from the galaxy .catalogs available now, and the dynamical analyses based on them

Up-down instability of binary black holes in numerical relativity

Binary black holes with spins that are aligned with the orbital angular momentum do not precess. However, post-Newtonian calculations predict that "up-down" binaries, in which the spin of the heavier (lighter) black hole is aligned (antialigned) with the orbital angular momentum, are unstable when the spins are slightly perturbed from perfect alignment. This instability provides a possible mechanism for the formation of precessing binaries in environments where sources are preferentially formed with (anti) aligned spins. In this paper, we present the first full numerical relativity simulations capturing this instability. These simulations span $\sim 100$ orbits and $\sim 3$-$5$ precession cycles before merger, making them some of the longest numerical relativity simulations to date. Initialized with a small perturbation of $1^{\circ}$-$10^{\circ}$, the instability causes a dramatic growth of the spin misalignments, which can reach $\sim 90^{\circ}$ near merger. We show that this leaves a strong imprint on the subdominant modes of the gravitational wave signal, which can potentially be used to distinguish up-down binaries from other sources. Finally, we show that post-Newtonian and effective-one-body approximants are able to reproduce the unstable dynamics of up-down binaries extracted from numerical relativity