68 research outputs found
Large-Scale Regular Morphological Patterns in the Radio Jet of NGC 6251
We report on large-scale, regular morphological patterns found in the radio
jet of the nearby radio galaxy NGC 6251. Investigating morphological properties
of this radio jet from the nucleus to a radial distance of 300 arcsec
( 140 kpc) mapped at 1662 MHz and 4885 MHz by Perley, Bridle, &
Willis, we find three chains, each of which consists of five radio knots. We
also find that eight radio knots in the first two chains consist of three small
sub-knots (the triple-knotty substructures). We discuss the observational
properties of these regular morphological patterns.Comment: 8 figures, 15 pages, accepted for publication in A
Is Thermal Expansion Driving the Initial Gas Ejection in NGC 6251?
In this paper, we explore the possibility that the radiative properties of
the most compact region in NGC 6251* may be understood in the same sense as Sgr
A*, though with some telling differences that may hint at the nature of jet
formation. We show that observations of this object with ASCA, ROSAT, HST and
VLBI together may be hinting at a picture in which Bondi-Hoyle accretion from
an ambient ionized medium feeds a standard disk accreting at ~ 4.0*10^{22} g
s^{-1}. Somewhere near the event horizon, this plasma is heated to >10^{11} K,
where it radiates via thermal synchrotron (producing a radio component) and
self-Comptonization (accounting for a nonthermal X-ray flux). This temperature
is much greater than its virial value and the hot cloud expands at roughly the
sound speed (~0.1c), after which it begins to accelerate on a parsec scale to
relativistic velocities. In earlier work, the emission from the extended jet
has been modeled successfully using nonthermal synchrotron self-Compton
processes, with a self-absorbed inner core. In the picture we are developing
here, the initial ejection of matter is associated with a self-absorbed thermal
radio component that dominates the core emission on the smallest scales. The
nonthermal particle distributions responsible for the emission in the extended
jet are then presumably energized, e.g., via shock acceleration, within the
expanding, hot gas. The power associated with this plasma represents an
accretion efficiency of about 0.54, requiring dissipation in a prograde disk
around a rapidly spinning black hole (with spin parameter a~1).Comment: 17 pages, 1 figures, to appear in Ap
Nuclear Disks of Gas and Dust in Early Type Galaxies and the Hunt for Massive Black Holes: Hubble Space Telescope Observations of NGC 6251
We discuss Hubble Space Telescope optical images and spectra of NGC 6251, a
giant E2 galaxy and powerful radio source at a distance of 106 Mpc (for H_0 =
70 km/s/Mpc). The galaxy is known to host a very well defined dust disk (O'Neil
et al. 1994); the exceptional resolution of our V and I images allows a
detailed study of the disk structure. Furthermore, narrow band images centered
on the Halpha+[NII] emission lines, reveal the presence of ionized gas in the
inner 0.3 arcsec of the disk. We used the HST/Faint Object Spectrograph with
the 0.09 arcsec aperture to study the velocity structure of the disk. Dynamical
models were constructed for two extreme (in terms of central concentration)
analytical representations of the stellar surface brightness profile, from
which the mass density and corresponding rotational velocity are derived
assuming a constant mass-to-light ratio (M/L)_V ~ 8.5 M_solar/L_solar. For both
representations of the stellar component, the models show that the gas is in
Keplerian motion around a central mass ~ 4 - 8 X 10^8 solar masses, and that
the contribution of radial flows to the velocity field is negligible.Comment: 45 pages, submitted to Ap
The role of initiator on the dispersibility of poly(styrene) microgels in non-aqueous solvents
Non-aqueous microgel particles are commonly synthesised in water, dried, and then redispersed in non-aqueous solvents. An important factor to consider when synthesising such particles is the initiator, which can determine how well the particles disperse in solvents. Polystyrene microgel particles were made with three different initiators. When a neutral, oil soluble initiator (azobisisobutyronitrile) was used the particles dispersed in toluene as well as cyclohexane and decalin. In contrast, anionic, water-soluble initiators (potassium persulfate or azobis(4-cyanovaleric acid)) created particles that only redispersed in toluene and not the other two solvents. Of the three considered, toluene is the best solvent for polystyrene and also has the highest polarizability, making it most effective at redispersing particles with polar or ionisable functional groups. Zeta potential and conductivity measurements, however, did not detect a direct relationship between particle charging and redispersibility. Oil soluble initiators result in “inside out” polymerisation where the initiator groups are buried inside the growing particle, whereas water-soluble initiators result in “outside in” polymerisation, with the polar initiator groups residing on the particle surface. By tailoring the ratio between water and oil soluble initiators, it may be possible to synthesise microgel particles with uniform or designed charge profiles from the core to the surface. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00396-017-4023-y) contains supplementary material, which is available to authorized users
Pain: metaphor, body, and culture in Anglo-American societies between the eighteenth and twentieth centuries
This article explores the relationship between metaphorical languages, body, and culture, and suggests that such an analysis can reveal a great deal about the meaning and experience of pain in Anglo-American societies between the eighteenth and twentieth centuries. It uses concepts within embodied cognition to speculate on how historians can write a history of sensation. Bodies are actively engaged in the linguistic processes and social interactions that constitute painful sensations. Language is engaged in a dialogue with physiological bodies and social environments. And culture collaborates in the creation of physiological bodies and metaphorical systems
A role for the collagen I/III and MMP-1/-13 genes in primary inguinal hernia?
BACKGROUND: Abnormal collagen metabolism is thought to play an important role in the development of primary inguinal hernia. This is underlined by detection of altered collagen metabolism and structural changes of the tissue in patients with primary inguinal hernia. However, it is still unknown whether these alterations reflect a basic dysfunction of the collagen synthesis, or of collagen degradation. METHODS: In the present study, we analysed type I and type III procollagen messenger ribonucleic acid (mRNA) and MMP-1 and MMP-13 mRNA in cultured fibroblasts from the skin of patients with primary inguinal hernia, and from patients without hernia (controls) by reverse transcription polymerase chain reaction (RT-PCR) and Northern Blot. RESULTS: The results indicated that the ratio of type I to type III procollagen mRNA was decreased in patients with primary hernia, showing significant differences as compared to controls (p = 0.01). This decrease was mainly due to the increase of type III procollagen mRNA. Furthermore, RT-PCR analysis revealed that the expression of MMP-1 mRNA in patients with primary hernia is equivalent to that of controls (p > 0.05). In addition, MMP-13 mRNA is expressed neither in patients with primary hernia nor in controls. CONCLUSION: We concluded that abnormal change of type I and type III collagen mRNAs contribute to the development of primary inguinal hernia, whereas the expressions of MMP-1 and MMP-13 mRNA appears not to be involved in the development of primary inguinal hernia. Thus, the knowledge on the transcriptional regulation of collagen in patients with primary inguinal hernia may help to understand the pathogenesis of primary inguinal hernia, and implies new therapeutic strategies for this disease
Gene expression and matrix turnover in overused and damaged tendons
Chronic, painful conditions affecting tendons, frequently known as tendinopathy, are very common types of sporting injury. The tendon extracellular matrix is substantially altered in tendinopathy, and these changes are thought to precede and underlie the clinical condition. The tendon cell response to repeated minor injuries or “overuse” is thought to be a major factor in the development of tendinopathy. Changes in matrix turnover may also be effected by the cellular response to physical load, altering the balance of matrix turnover and changing the structure and composition of the tendon. Matrix turnover is relatively high in tendons exposed to high mechanical demands, such as the supraspinatus and Achilles, and this is thought to represent either a repair or tissue maintenance function. Metalloproteinases are a large family of enzymes capable of degrading all of the tendon matrix components, and these are thought to play a major role in the degradation of matrix during development, adaptation and repair. It is proposed that some metalloproteinase enzymes are required for the health of the tendon, and others may be damaging, leading to degeneration of the tissue. Further research is required to investigate how these enzyme activities are regulated in tendon and altered in tendinopathy. A profile of all the metalloproteinases expressed and active in healthy and degenerate tendon is required and may lead to the development of new drug therapies for these common and debilitating sports injuries
Contemporaneous VLBA 5 GHz Observations of LAT-Detected Blazars
The radio properties of blazars detected by the Large Area Telescope (LAT) on
board the Fermi Gamma-ray Space Telescope have been observed contemporaneously
by the Very Long Baseline Array (VLBA). In total, 232 sources were observed
with the VLBA. Ninety sources that were previously observed as part of the VLBA
Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well
as 142 sources not found in VIPS. This very large, flux-limited sample of
active galactic nuclei (AGN) provides insights into the mechanism that produces
strong gamma-ray emission. In particular, we see that gamma-ray emission is
related to strong, uniform magnetic fields in the cores of the host AGN.
Included in this sample are non-blazar AGN such as 3C84, M82, and NGC 6251. For
the blazars, the total VLBA radio flux density at 5 GHz correlates strongly
with gamma-ray flux. The LAT BL Lac objects tend to be similar to the non-LAT
BL Lac objects, but the LAT flat-spectrum radio quasars (FSRQs) are
significantly different from the non-LAT FSRQs. Strong core polarization is
significantly more common among the LAT sources, and core fractional
polarization appears to increase during LAT detection.Comment: 47 pages, 12 figures, accepted for publication in The Astrophysical
Journa
The Porcelain Crab Transcriptome and PCAD, the Porcelain Crab Microarray and Sequence Database
BACKGROUND: With the emergence of a completed genome sequence of the freshwater crustacean Daphnia pulex, construction of genomic-scale sequence databases for additional crustacean sequences are important for comparative genomics and annotation. Porcelain crabs, genus Petrolisthes, have been powerful crustacean models for environmental and evolutionary physiology with respect to thermal adaptation and understanding responses of marine organisms to climate change. Here, we present a large-scale EST sequencing and cDNA microarray database project for the porcelain crab Petrolisthes cinctipes. METHODOLOGY/PRINCIPAL FINDINGS: A set of approximately 30K unique sequences (UniSeqs) representing approximately 19K clusters were generated from approximately 98K high quality ESTs from a set of tissue specific non-normalized and mixed-tissue normalized cDNA libraries from the porcelain crab Petrolisthes cinctipes. Homology for each UniSeq was assessed using BLAST, InterProScan, GO and KEGG database searches. Approximately 66% of the UniSeqs had homology in at least one of the databases. All EST and UniSeq sequences along with annotation results and coordinated cDNA microarray datasets have been made publicly accessible at the Porcelain Crab Array Database (PCAD), a feature-enriched version of the Stanford and Longhorn Array Databases. CONCLUSIONS/SIGNIFICANCE: The EST project presented here represents the third largest sequencing effort for any crustacean, and the largest effort for any crab species. Our assembly and clustering results suggest that our porcelain crab EST data set is equally diverse to the much larger EST set generated in the Daphnia pulex genome sequencing project, and thus will be an important resource to the Daphnia research community. Our homology results support the pancrustacea hypothesis and suggest that Malacostraca may be ancestral to Branchiopoda and Hexapoda. Our results also suggest that our cDNA microarrays cover as much of the transcriptome as can reasonably be captured in EST library sequencing approaches, and thus represent a rich resource for studies of environmental genomics
Urban futures and the code for sustainable homes
Copyright © 2012 ICE Publishing Ltd. Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.A 6?6 ha (66 000 m2) regeneration site, commonly referred to as Luneside East, is to be turned from a run down,
economically under-achieving area of Lancaster, UK, into a new, distinctive, vibrant, sustainable quarter of the city. As
a result several aspects of water planning for 350 new homes and 8000 m2 of workspace needed to be considered
before any infrastructure investment was undertaken. This included assessment of the future capacity requirements
(i.e. inflows and outflows) for water infrastructure (i.e. mains water supply, wastewater disposal, rainwater storage
and stormwater disposal) much of which will be located underground. This paper looks at the implications of various
water management strategies on the Luneside East site (e.g. water-efficient appliances, greywater recycling and
rainwater harvesting) in line with current policy measures that focus on technology changes alone (e.g. the code for
sustainable homes). Based on these findings this paper outlines some basic implications for technological resilience
discussed in the context of four ‘world views’ – that is, the urban futures scenarios considered in this special issue.
Conclusions are drawn as to how far this can take engineers, planners and developers in understanding and planning
for resilient water infrastructure within a development like Luneside East
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