4,051 research outputs found
Volume integrals associated with the inhomogeneous Helmholtz equation. Part 1: Ellipsoidal region
Problems of wave phenomena in fields of acoustics, electromagnetics and elasticity are often reduced to an integration of the inhomogeneous Helmholtz equation. Results are presented for volume integrals associated with the Helmholtz operator, nabla(2) to alpha(2), for the case of an ellipsoidal region. By using appropriate Taylor series expansions and multinomial theorem, these volume integrals are obtained in series form for regions r 4' and r r', where r and r' are distances from the origin to the point of observation and source, respectively. Derivatives of these integrals are easily evaluated. When the wave number approaches zero, the results reduce directly to the potentials of variable densities
The RNA-binding protein LARP1 is a post-transcriptional regulator of survival and tumorigenesis in ovarian cancer
RNA-binding proteins (RBPs) are increasingly identified as post-transcriptional drivers of cancer progression. The RBP LARP1 is an mRNA stability regulator, and elevated expression of the protein in hepatocellular and lung cancers is correlated with adverse prognosis. LARP1 associates with an mRNA interactome that is enriched for oncogenic transcripts. Here we explore the role of LARP1 in epithelial ovarian cancer, a disease characterized by the rapid acquisition of resistance to chemotherapy through the induction of pro-survival signalling. We show, using ovarian cell lines and xenografts, that LARP1 is required for cancer cell survival and chemotherapy resistance. LARP1 promotes tumour formation in vivo and maintains cancer stem cell-like populations. Using transcriptomic analysis following LARP1 knockdown, cross-referenced against the LARP1 interactome, we identify BCL2 and BIK as LARP1 mRNA targets. We demonstrate that, through an interaction with the 3 untranslated regions (3 UTRs) of BCL2 and BIK, LARP1 stabilizes BCL2 but destabilizes BIK with the net effect of resisting apoptosis. Together, our data indicate that by differentially regulating the stability of a selection of mRNAs, LARP1 promotes ovarian cancer progression and chemotherapy resistance
Decreasing Elevator Travel in Women With Sign Prompts Encouraging Stair Use
The purpose of this study was to determine if motivational signs encouraging stair use could decrease elevator travel in women. Observational data coded women using the elevator by direction of travel, ethnicity, and weight. After a 2-week baseline signs encouraging stair use were placed throughout the academic building. The signs were removed for a week of follow-up observations. An 8-question survey was also administered to 61 women. A trend towards significant decreases in elevator travel was found (p=.076). The greatest decreases occurred in African American, and overweight women. Eighty-eight percent of those surveyed, who were elevator users, reported the signs did prompt them to use the stairs over the elevator. The trend towards significance, coupled with the survey showing a high influence of the signs suggests a multi-placement prompt strategy may be beneficial in decreasing sedentary methods of travel in buildings where the probability of repeat travel is high
Bending crystals: Emergence of fractal dislocation structures
We provide a minimal continuum model for mesoscale plasticity, explaining the
cellular dislocation structures observed in deformed crystals. Our dislocation
density tensor evolves from random, smooth initial conditions to form
self-similar structures strikingly similar to those seen experimentally -
reproducing both the fractal morphologies and some features of the scaling of
cell sizes and misorientations analyzed experimentally. Our model provides a
framework for understanding emergent dislocation structures on the mesoscale, a
bridge across a computationally demanding mesoscale gap in the multiscale
modeling program, and a new example of self-similar structure formation in
non-equilibrium systems.Comment: 4 pages, 4 figures, 5 movies (They can be found at
http://www.lassp.cornell.edu/sethna/Plasticity/SelfSimilarity.html .) In
press at Phys. Rev. Let
Spectral properties of the narrow-line region in Seyfert galaxies selected from the SDSS-DR7
Although the properties of the narrow-line region (NLR) of active galactic
nuclei(AGN) have been deeply studied by many authors in the past three decades,
many questions are still open. The main goal of this work is to explore the NLR
of Seyfert galaxies by collecting a large statistical spectroscopic sample of
Seyfert 2 and Intermediate-type Seyfert galaxies having a high signal-to-noise
ratio in order to take advantage of a high number of emission-lines to be
accurately measured. 2153 Seyfert 2 and 521 Intermediate-type Seyfert spectra
were selected from Sloan Digital Sky Survey - Data Release 7 (SDSS-DR7) with a
diagnostic diagram based on the oxygen emission-line ratios. All the
emission-lines, broad components included, were measured by means of a
self-developed code, after the subtraction of the stellar component. Physical
parameters, such as internal reddening, ionization parameter, temperature,
density, gas and stellar velocity dispersion were determined for each object.
Furthermore, we estimated mass and radius of the NLR, kinetic energy of the
ionized gas, and black-hole accretion rate. From the emission-line analysis and
the estimated physical properties, it appears that the NLR is similar in
Seyfert 2 and Intermediate-Seyfert galaxies. The only differences, lower
extinction, gas kinematics in general not dominated by the host galaxy
gravitational potential and higher percentage of [O III]5007 blue asymmetries
in Intermediate-Seyfert can be ascribed to an effect of inclination of our line
of sight with respect to the torus axis.Comment: Accepted for publication in MNRA
Optical Emission Lines and the X-Ray Properties of Type 1 Seyfert Galaxies
In this contribution we report on the study of the optical emission lines and
X-ray spectra of a sample of Type 1 AGNs, collected at the Sloan Digital Sky
Survey database and observed by the XMM Newton satellite. Exploiting the
different instruments carried onboard XMM, we identify the spectral components
of the soft and hard energy bands (in the range from 0.3 keV up to 10 keV). The
properties of the X-ray continuum and of the Fe Kalpha line feature are
investigated in relation to the optical broad emission line profiles and
intensity ratios. The resulting picture of emission, absorption and reflection
processes is interpreted by means of a BLR structural model that was developed
on the basis of independent optical and radio observations.Comment: 6 pages, 3 figures, Proceedings of the VIII Serbian Conference on
Spectral Line Shapes in Astrophysics, accepted for publication on Baltic
Astronomy. Corrected typos in V
The Relation between Nuclear Activity and Stellar Mass in Galaxies
The existence of correlations between nuclear properties of galaxies, such as
the mass of their central black holes, and larger scale features, like the
bulge mass and luminosity, represent a fundamental constraint on galaxy
evolution. Although the actual reasons for these relations have not yet been
identified, it is widely believed that they could stem from a connection
between the processes that lead to black hole growth and stellar mass assembly.
The problem of understanding how the processes of nuclear activity and star
formation can affect each other became known to the literature as the
Starburst-AGN connection. Despite years of investigation, the physical
mechanisms which lie at the basis of this relation are known only in part. In
this work, we analyze the problem of star formation and nuclear activity in a
large sample of galaxies. We study the relations between the properties of the
nuclear environments and of their host galaxies. We find that the mass of the
stellar component within the galaxies of our sample is a critical parameter,
that we have to consider in an evolutionary sequence, which provides further
insight in the connection between AGN and star formation processes.Comment: 13 pages, 10 figures, accepted for publication on MNRAS. Reference to
the mass derivation procedure correcte
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