2,158 research outputs found
Evidence for a Massive Dark Object in NGC 4350
In this work we build a detailed dynamic model for a S0 galaxy possibly
hosting a central massive dark object (MDO). We show that the photometric
profiles and the kinematics along the major and minor axes, including the h3
and h4 profiles, imply the presence of a central MDO of mass M = 1.5 - 9.7 10^8
solar masses, i.e. 0.3-2.8% of the mass derived for the stellar spheroidal
component. Models without MDO are unable to reproduce the kinematic properties
of the inner stars and of the rapidly rotating nuclear gas.
The stellar population comprise of an exponential disc (27% of the light) and
a diffuse spheroidal component (73% of the light) that cannot be represented by
a simple de Vaucouleurs profile at any radius. The M/L ratios we found for the
stellar components (respectively 3.3 and 6.6) are typical of those of disc and
elliptical galaxies.Comment: 9 pages, 4 encapsulated postscript figures. Requires mn.sty,
psfig.sty. Accepted for publication in MNRA
Disfranchisement, Women\u27s Suffrage and the Failure of Florida\u27s Grandfather Clause
Following the adoption of the Constitution of 1885, Florida joined its sister southern states in enacting a series of election laws aimed at disfranchising black voters. This statutory labyrinth, with the Democratic party’s white primary system as its centerpiece, had all but excluded the state’s African-American citizens from the political arena by 1913. Although virtually complete in its practical effects, that process legally operated only in the primary elections. African-American males remained technically eligible to vote in general elections if their poll taxes were paid. In the same period, women’s suffrage was intruding on the existing political structure from another direction with a momentum that clearly portended ultimate success. Although both movements focused on the most fundamental dynamic of American politics, the right to vote, each ran to its historical conclusion on essentially separate courses. Yet, for a brief period between 1915 and 1916, the two converged in a confusing and almost forgotten episode of Florida political history
Railroads, Farmers and Senatorial Politics: The Florida Commission in the 1890s
The 1887 Florida Legislature created the state’s first Railroad Commission to curb monopoly abuses by railroad companies. 1 The legislation, which vested regulatory jurisdiction in a three-person commission appointed by the governor, was popular and suited to the reform tenor of the times. It had passed unanimously in the house and with only three dissenting votes in the senate. 2 Yet, in a peculiar twist of Florida political history, the commission’s statutory basis was abruptly repealed only four years later. Florida’s intrastate rail service was left once again unfettered by regulatory constraints.3 Then, six years later, the legislature reestablished the commission in almost its original form.4 Such quick reversals of political direction strongly infer that collateral issues dominated the outcome on the main question of railroad regulation. The episode prompts a two-fold question: Why the repeal in the first place, and why reenactment six years later? This article explores the interrelated dynamics of senatorial elections prior to enactment of the 17th Amendment, the agrarian reform movement and railroad politics in the context of those questions
On syntheses of the X-ray background with power-law sources
The conditions under which the combined emission from power law sources can mimic the X-ray background (XRB) spectrum in the 3-50 keV range are considered in view of HEAO 1 A-2 experiment measurements, and it is confirmed that a good fit may be obtained. The required spectral properties of the component sources differ, however, from those observed for local active galactic nuclei. Constraints are deduced for both the low luminosity extension and evolution of such local objects, and it is shown that any other class of sources contributing to the X-ray background must be characterized by an energy spectral index lower than about 0.4, which is the mean index of the XRB, and exhibit sleeper spectra at higher energies
Spectroscopy of moderately high-redshift RCS-1 clusters
We present spectroscopic observations of 11 moderately high-redshift (z~0.7-
1.0) clusters from the first Red-Sequence Cluster Survey (RCS-1). We find
excellent agreement between the red-sequence estimated redshift and the
spectroscopic redshift, with a scatter of 10% at z>0.7. At the high-redshift
end (z>~0.9) of the sample, we find two of the systems selected are projections
of pairs of comparably rich systems, with red-sequences too close to
discriminate in (R-z') colour. In one of these systems, the two components are
close enough to be physically associated. For a subsample of clusters with
sufficient spectroscopic members, we examine the correlation between B_gcR
(optical richness) and the dynamical mass inferred from the velocity
dispersion. We find these measurements to be compatible, within the relatively
large uncertainties, with the correlation established at lower redshift for the
X-ray selected CNOC1 clusters and also for a lower redshift sample of RCS-1
clusters. Confirmation of this and calibration of the scatter in the relation
will require larger samples of clusters at these and higher redshifts.
[abridged]Comment: AJ accepted. 30 pages, 7 figures (figure 5 reduced quality
CAIRNS: The Cluster And Infall Region Nearby Survey I. Redshifts and Mass Profiles
The CAIRNS (Cluster And Infall Region Nearby Survey) project is a
spectroscopic survey of the infall regions surrounding eight nearby, rich,
X-ray luminous clusters of galaxies. We collect 15665 redshifts (3471 new or
remeasured) within \sim 5-10 Mpc of the centers of the clusters, making it the
largest study of the infall regions of clusters. We determine cluster
membership and the mass profiles of the clusters based on the phase space
distribution of the galaxies. All of the clusters display decreasing velocity
dispersion profiles. The mass profiles are fit well by functional forms based
on numerical simulations but exclude an isothermal sphere. Specifically, NFW
and Hernquist models provide good descriptions of cluster mass profiles to
their turnaround radii. Our sample shows that the predicted infall pattern is
ubiquitous in rich, X-ray luminous clusters over a large mass range. The
caustic mass estimates are in excellent agreement with independent X-ray
estimates at small radii and with virial estimates at intermediate radii. The
mean ratio of the caustic mass to the X-ray mass is 1.03\pm0.11 and the mean
ratio of the caustic mass to the virial mass (when corrected for the surface
pressure term) is 0.93\pm0.07. We further demonstrate that the caustic
technique provides reasonable mass estimates even in merging clusters.Comment: 54 pages, 18 figures, to appear in The Astronomical Journa
Vascular endothelial growth factor C disrupts the endothelial lymphatic barrier to promote colorectal cancer invasion
Background & Aims
Colorectal cancer (CRC) is highly metastatic. Metastases spread directly into local tissue or invade distant organs via blood and lymphatic vessels, but the role of lymphangiogenesis in CRC progression has not been determined. Lymphangiogenesis is induced via vascular endothelial growth factor C (VEGFC) activation of its receptor, VEGFR3; high levels of VEGFC have been measured in colorectal tumors undergoing lymphangiogenesis, and correlated with metastasis. We investigated VEGFC signaling and lymphatic barriers in human tumor tissues and mice with orthotopic colorectal tumors.
Methods
We performed immunohistochemical, immunoblot, and real-time PCR analyses of colorectal tumor specimens collected from patients; healthy intestinal tissues collected during surgeries of patients without CRC were used as controls. CT26 CRC cells were injected into the distal posterior rectum of BALB/c-nude mice. Mice were given injections of an antibody against VEGFR3 or an adenovirus encoding human VEGFC before orthotopic tumors and metastases formed. Lymph node, lung, and liver tissues were collected and evaluated by flow cytometry. We measured expression of vascular endothelial cadherin (CDH5) on lymphatic vessels in mice and in human intestinal lymphatic endothelial cells.
Results
Levels of podoplanin (a marker of lymphatic vessels), VEGFC, and VEGFR3 were increased in colorectal tumor tissues, compared with controls. Mice that expressed VEGFC from the adenoviral vector had increased lymphatic vessel density and more metastases in lymph nodes, lungs, and livers, compared with control mice. Anti-VEGR3 antibody reduced numbers of lymphatic vessels in colons and prevented metastasis. Expression of VEGFC compromised the lymphatic endothelial barrier in mice and endothelial cells, reducing expression of CDH5, increasing permeability, and increasing trans-endothelial migration by CRC cells. Opposite effects were observed in mice and cells when VEGFR3 was blocked.
Conclusions
VEGFC signaling via VEGFR3 promotes lymphangiogenesis and metastasis by orthotopic colorectal tumors in mice and reduces lymphatic endothelial barrier integrity. Levels of VEGFC and markers of lymphatic vessels are increased in CRC tissues from patients, compared with healthy intestine. Strategies to block VEGFR3 might be developed to prevent CRC metastasis in patients
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