799 research outputs found
3C 216: A Powerful FRII Seyfert 1 Galaxy
3C 216 has a weak accretion flow luminosity, well below the Seyfert1/QSO
dividing line, weak broad emission lines (BELs) and powerful radio lobes. As a
consequence of the extreme properties of 3C 216, it is the most convincing
example known of an FR II radio source that is kinetically dominated: the jet
kinetic luminosity, , is larger than the total thermal luminosity (IR to
X-ray) of the accretion flow, . Using three independent estimators for
the central black hole mass, we find that the jet in 3C 216 is very
super-Eddington, , where is the long
term time averaged , calculated at 151 MHz. It is argued that 3C 216
satisfies the contemporaneous kinetically dominated condition, , either presently or in the past based on the rarity of
quasars. The existence of AGN is a strong constraint
on the theory of the central engine of FRII radio sources
Probing the pc- and kpc-scale environment of the powerful radio galaxy Hercules A
We present the kpc-scale behaviour of the powerful extragalactic radio source
Hercules A and the behaviour of the intracluster gas in which the radio source
is situated. We have found that Hercules A exhibits a strong Laing-Garrington
effect. The X-ray observations have revealed an extended X-ray emission
elongated along the radio galaxy axis. The estimated temperature of the cluster
is kT = 2.45 keV and the central electron density is no~7.8 x 10^(-3) cm^(-3)
which reveals a hot, dense environment in which Hercules A is situated. From
the combined study of the radio and X-ray data we have estimated a central
value of 3<Bo (muG)<9. We also present the most recent results from the
analysis of the radio data on the pc-scale structure of the radio galaxy,
observed at 18 cm by the EVN-MERLIN array. A faint but compact radio source,
coincident with the optical centre of Hercules A was detected by the EVN at 18
mas resolution. The total flux density of the EVN core is 14.6 mJy. Its angular
size is 18 x 7 mas with a position angle of ~139 degrees. There is also
evidence for extended emission in the NW-SE direction, most probably from the
eastern pc-scale jet. If this is true then there is a misalignment between the
direction of the pc-eastern and the aligned kpc-scale jets of ~35 degrees.Comment: 7 pages, 2 figures, Submitted to PAS
Characterization of a mouse cortical collecting duct cell line
Characterization of a mouse cortical collecting duct cell line. A cortical collecting duct (CCD) cell line has been developed from a mouse transgenic for the early region of simian virus 40, Tg(SV40E)Bri/7. CCDs were microdissected and placed on collagen gels. Monolayers were subsequently subcultured onto permeable collagen membranes and maintained in serum-supplemented medium. One line, designated M-1, retained many characteristics of the CCD, including a typical epithelial appearance and CCD-specific antigens. M-1 cells, when grown in monolayers on permeable supports, exhibited a high transepi-thelial resistance (885.7 ± 109.6 ohms/cm2) and developed a lumen negative transepithelial potential difference (PD) of -45.7 ± 3.5mV. The associated short-circuit current (SCC) averaged 71.8 ± 10.3 ”A/cm2, and was reduced by 95% by luminal application of amiloride. The cultured cells responded to arginine vasopressin (AVP) with a significant increase in SCC. M-1 cells generated significant transepithelial solute gradients. After 24 hours incubation, the composition of the luminal (L) and basolateral (B) media (in mM) was: [Na+], L = 106.7 ± 0.9 and B = 127.4 ± 0.4; [K+], L = 8.6 ± 0.6 and B = 2.1 ± 0.3; [Cl], L = 68.6 ± 5.8 and B = 101.8 ± 6.6; [HCO3], L = 15.5 ± 1.5 and B = 8.6 ± 1.2; while pH was 7.16 ± 0.03 at the luminal and 6.94 ± 0.03 at the basolateral side. The formation of these concentration gradients indicates that the CCD cultures absorb Na+ and Cl- and secrete K+. Lactate accumulated predominantly at the basolateral side (L = 7.1 ± 0.44 and B = 17.5 ± 0.52 mM); osmotic concentration was 272 ± 1.4 at the luminal and 290 ±3.0 mOsm/kg at the basolateral side. These data demonstrate that the M-1 cell line retains many phenotypic properties of the CCD epithelium and thus should prove useful as a model in studying mechanisms of ion transport in this segment
The inner radio jet region and the complex environment of SS433
We present multi-frequency VLBA+VLA observations of SS433 at 1.6, 5 and 15
GHz. These observations provide the highest angular resolution radio spectral
index maps ever made for this object. Motion of the components of SS433 during
the observation is detected. In addition to the usual VLBI jet structure, we
detect two radio components in the system at an anomalous position angle. These
newly discovered radio emitting regions might be related to a wind-like
equatorial outflow or to an extension of the accretion disk. We show that the
radio core component is bifurcated with a clear gap between the eastern and
western wings of emission. Modelfitting of the precessing jets and the moving
knots of SS433 shows that the kinematic centre -- i.e. the binary -- is in the
gap between the western and eastern radio core components. Spectral properties
and observed core position shifts suggest that we see a combined effect of
synchrotron self-absorption and external free-free absorption in the innermost
AU-scale region of the source. The spatial distribution of the ionized matter
is probably not spherically symmetric around the binary, but could be
disk-like.Comment: Accepted for publication by Astronomy and Astrophysic
Does the Supreme Court Follow the Economic Returns? A Response to A Macrotheory of the Court
Today, there is a widespread idea that parents need to learn how to carry out their roles as parents. Practices of parental learning operate throughout society. This article deals with one particular practice of parental learning, namely nanny TV, and the way in which ideal parents are constructed through such programmes. The point of departure is SOS family, a series broadcast on Swedish television in 2008. Proceeding from the theorising of governmentality developed in the wake of the work of Michel Foucault, we analyse the parental ideals conveyed in the series, as an example of the way parents are constituted as subjects in the âadvanced liberal societyâ of today. The ideal parent is a subject who, guided by the coach, is constantly endeavouring to achieve a makeover. The objective of this endeavour, however, is self-control, whereby the parents will in the end become their own coaches.
Small RNA in the nucleus: the RNA-chromatin ping-pong
Eukaryotes use several classes of small RNA molecules to guide diverse protein machineries to target messenger RNA. The role of small RNA in post-transcriptional regulation of mRNA stability and translation is now well established. Small RNAs can also guide sequence-specific modification of chromatin structure and thus contribute to establishment and maintenance of distinct chromatin domains. In this review we summarize the model for the inter-dependent interaction between small RNA and chromatin that has emerged from studies on fission yeast and plants. We focus on recent results that link a distinct class of small RNAs, the piRNAs, to chromatin regulation in animals
To be or not to be a piRNA: genomic origin and processing of piRNAs
Piwi-interacting RNAs (piRNAs) originate from genomic
regions dubbed piRNA clusters. How cluster transcripts
are selected for processing into piRNAs is not
understood. We discuss evidence for the involvement
of chromatin structure and maternally inherited
piRNAs in determining their fate
Dense Packings of Congruent Circles in Rectangles with a Variable Aspect Ratio
We use computational experiments to find the rectangles of minimum area into
which a given number n of non-overlapping congruent circles can be packed. No
assumption is made on the shape of the rectangles. Most of the packings found
have the usual regular square or hexagonal pattern. However, for 1495 values of
n in the tested range n =< 5000, specifically, for n = 49, 61, 79, 97, 107,...
4999, we prove that the optimum cannot possibly be achieved by such regular
arrangements. The evidence suggests that the limiting height-to-width ratio of
rectangles containing an optimal hexagonal packing of circles tends to
2-sqrt(3) as n tends to infinity, if the limit exists.Comment: 21 pages, 13 figure
Gallstone Ileus, Bouveret's Syndrome and Choledocholithiasis in a Patient with Billroth II Gastrectomy â A Case Report of Combined Endoscopic and Surgical Therapy
Intestinal obstruction due to gallstone is a rare, but quite severe gastrointestinal disorder, which always requires a rapid and correct diagnosis to achieve optimal therapy. Digestive endoscopy is an important method to determine the level of the bowel obstruction and to plan an optimal therapeutic strategy. Our present case demonstrates that in a high-risk patient, a combined endoscopic and surgical therapy is the best choice to solve the obstruction of the colon, of the stomach and of the common bile duct caused by multiple gallstones
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