6,889 research outputs found
Legitimating inaction : differing identity constructions of the Scots language.
The Scots language plays a key role in the political and cultural landscape of contemporary Scotland. From a discourse-historical perspective, this article explores how language ideologies about the Scots language are realized linguistically in a so-called âlanguages strategyâ drafted by the Scottish Executive, and in focus groups consisting of Scottish people. This article shows that although the decline of Scots is said to be a âtragedyâ, focus group participants seem to reject the notion of Scots as a viable, contemporary language that can be used across a wide range of registers. The policy document also seems to construct Scots in very positive terms, but is shown to be unhelpful or potentially even damaging in the process of changing public attitudes to Scots
Constraining the origin of UHECRs and astrophysical neutrinos
We explore the possibility of a common origin of ultrahigh energy cosmic rays (UHECRs) and astrophysical neutrinos and further constrain sources which are consistent with this possibility. We show that the common origin hypothesis can be satisfied for the Sibyll2.3c hadronic interaction model but is difficult to accommodate for EPOS-LHC, showing that multimessenger analyses have the power to also constrain hadronic physics beyond LHC energies. We constrain properties of UHECR source environments (and potentially astrophysical neutrino sources), including their photon temperature, gas density, size, magnetic field strength and coherence length, using UHECR and neutrino spectra and composition. Our analysis represents a new type of information on UHECR sources, independent of the mechanism responsible for the UHECR acceleration
Sub 20 nm Short Channel Carbon Nanotube Transistors
Carbon nanotube field-effect transistors with sub 20 nm long channels and
on/off current ratios of > 1000000 are demonstrated. Individual single-walled
carbon nanotubes with diameters ranging from 0.7 nm to 1.1 nm grown from
structured catalytic islands using chemical vapor deposition at 700 degree
Celsius form the channels. Electron beam lithography and a combination of HSQ,
calix[6]arene and PMMA e-beam resists were used to structure the short channels
and source and drain regions. The nanotube transistors display on-currents in
excess of 15 microA for drain-source biases of only 0.4 Volt.Comment: Nano Letters in pres
On the Nature of Intrinsic Absorption in Reddened Seyfert 1 Galaxies
We discuss the origin of the ``dusty lukewarm absorber'', which we previously
identified in the reddened Seyfert 1 galaxies NGC 3227 and Akn 564. This
absorber is characterized by saturated UV absorption lines (C IV, N V) near the
systemic velocity of the host galaxy, and is likely responsible for reddening
both the continuum and the emission lines (including those from the narrow-line
region) from these Seyferts. From a large sample of Seyfert 1 galaxies, we find
that continuum reddening (as measured by UV color) tends to increase with
inclination of the host galaxy. Furthermore, reddened, inclined Seyfert
galaxies observed at moderate to high spectral resolution all show evidence for
dusty lukewarm absorbers. We suggest that these absorbers lie in the plane of
the host galaxy at distances > 100 pc from the nucleus, and are physically
distinct from the majority of intrinsic absorbers that are outflowing from the
nucleus.Comment: 14 pages, including 2 figures, accepted for publication in the
Astrophysical Journal (Letters
Heparan sulfate proteoglycans are concentrated on the sinusoidal plasmalemmal domain and in intracellular organelles of hepatocytes
NICMOS Imaging of Molecular Hydrogen Emission in Seyfert Galaxies
We present NICMOS imaging of broad band and molecular hydrogen emission in
Seyfert galaxies. In 6 of 10 Seyferts we detect resolved or extended emission
in the 1-0 S(1) 2.121 or 1-0 S(3) 1.9570 micron molecular hydrogen lines. We
did not detect emission in the most distant galaxy or in the 2 Seyfert 1
galaxies in our sample because of the luminosity of the nuclear point sources.
In NGC 5643, NGC 2110 and MKN 1066, molecular hydrogen emission is detected in
the extended narrow line region on scales of a few hundred pc from the nucleus.
Emission is coincident with [OIII] and H alpha+[NII] line emission. This
emission is also near dust lanes observed in the visible to near-infrared color
maps suggesting that a multiphase medium exists near the ionization cones and
that the morphology of the line emission is dependent on the density of the
ambient media. The high 1-0 S(1) or S(3) H2 to H alpha flux ratio suggests that
shock excitation of molecular hydrogen (rather than UV fluorescence) is the
dominant excitation process in these extended features. In NGC 2992 and NGC
3227 the molecular hydrogen emission is from 800 and 100 pc diameter `disks'
(respectively) which are not directly associated with [OIII] emission and are
near high levels of extinction (AV > 10). In NGC 4945 the molecular hydrogen
emission appears to be from the edge of a 100 pc superbubble. In these 3
galaxies the molecular gas could be excited by processes associated with local
star formation. We confirm previous spectroscopic studies finding that no
single mechanism is likely to be responsible for the molecular hydrogen
excitation in Seyfert galaxies.Comment: submitted to Ap
The Seyfert-Starburst Connection in X-rays. II. Results and Implications
We present the results of X-ray imaging and spectroscopic analysis of a
sample of Seyfert 2 galaxies that contain starbursts, based on their optical
and UV characteristics. These composite galaxies exhibit extended, soft,
thermal X-ray emission, which we attribute to their starburst components.
Comparing their X-ray and far-infrared properties with ordinary Seyfert and
starburst galaxies, we identify the spectral characteristics of their various
intrinsic emission sources. The observed far-infrared emission of the composite
galaxies may be associated almost exclusively with star formation, rather than
the active nucleus. The ratio of the hard X-ray luminosity to the far-infrared
and [O III] 5007 luminosity distinguishes most of these composite galaxies from
``pure'' Seyfert 2 galaxies, while their total observed hard X-ray luminosity
distinguishes them from ``pure'' starbursts. The hard nuclear X-ray source is
generally heavily absorbed (N_H > 10^{23} cm^{-2}) in the composite galaxies.
Based on these results, we suggest that the interstellar medium of the nuclear
starburst is a significant source of absorption. The majority of the sample are
located in groups or are interacting with other galaxies, which may trigger the
starburst or allow rapid mass infall to the central black hole, or both. We
conclude that starbursts are energetically important in a significant fraction
of active galaxies, and starbursts and active galactic nuclei may be part of a
common evolutionary sequence.Comment: 16 pages including 8 figures and 5 tables; to appear in the ApJ, Mar.
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