618 research outputs found
The Imprint of Gravitational Waves on the Cosmic Microwave Background
Long-wavelength gravitational waves can induce significant temperature
anisotropy in the cosmic microwave background. Distinguishing this from
anisotropy induced by energy density fluctuations is critical for testing
inflationary cosmology and theories of large-scale structure formation. We
describe full radiative transport calculations of the two contributions and
show that they differ dramatically at angular scales below a few degrees. We
show how anisotropy experiments probing large- and small-angular scales can
combine to distinguish the imprint due to gravitational waves.Comment: 11 pages, Penn Preprint-UPR-
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Identification of Orch3, a Locus Controlling Dominant Resistance to Autoimmune Orchitis, as Kinesin Family Member 1C
Experimental autoimmune orchitis (EAO), the principal model of non-infectious testicular inflammatory disease, can be induced in susceptible mouse strains by immunization with autologous testicular homogenate and appropriate adjuvants. As previously established, the genome of DBA/2J mice encodes genes that are capable of conferring dominant resistance to EAO, while the genome of BALB/cByJ mice does not and they are therefore susceptible to EAO. In a genome scan, we previously identified Orch3 as the major quantitative trait locus controlling dominant resistance to EAO and mapped it to chromosome 11. Here, by utilizing a forward genetic approach, we identified kinesin family member 1C (Kif1c) as a positional candidate for Orch3 and, using a transgenic approach, demonstrated that Kif1c is Orch3. Mechanistically, we showed that the resistant Kif1c allele leads to a reduced antigen-specific T cell proliferative response as a consequence of decreased MHC class II expression by antigen presenting cells, and that the L→P and S→P polymorphisms distinguishing the BALB/cByJ and DBA/2J alleles, respectively, can play a role in transcriptional regulation. These findings may provide mechanistic insight into how polymorphism in other kinesins such as KIF21B and KIF5A influence susceptibility and resistance to human autoimmune diseases
Effective decellularisation of human saphenous veins for biocompatible arterial tissue engineering applications:Bench optimisation and feasibility in vivo testing
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Use of a fluorinated probe to quantitatively monitor amino acid binding preferences of ruthenium(ii) arene complexes.
In order to address outstanding questions about ruthenium complexes in complex biological solutions, 19F NMR spectroscopy was used to follow the binding preferences between fluorinated RuII(η6-arene)(bipyridine) complexes and protected amino acids and glutathione. Reporting what ruthenium compounds bind to in complex environments has so far been restricted to relatively qualitative methods, such as mass spectrometry and X-ray spectroscopic methods; however, quantitative information on the species present in the solution phase cannot be inferred from these techniques. Furthermore, using 1H NMR, in water, to distinguish and monitor a number of different complex RuII(η6-arene) adducts forming is challenging. Incorporating an NMR active heteroatom into ruthenium organometallic complexes provides a quantitative, diagnostic 'fingerprint' to track solution-phase behaviour and allow for unambiguous assignment of any given adduct. The resulting 19F NMR spectra show for the first time the varied, dynamic behaviour of organoruthenium compounds when exposed to simple biomolecules in complex mixtures. The rates of formation of the different observed species are dramatically influenced by the electronic properties at the metal, even in a closely related series of complexes in which only the electron-donating properties of the arene ligand are altered. Preference for cysteine binding is absolute: the first quantitative solution-phase evidence of such behaviour
SPIRITS 15c and SPIRITS 14buu: Two Obscured Supernovae in the Nearby Star-Forming Galaxy IC 2163
SPIRITS---SPitzer InfraRed Intensive Transients Survey---is an ongoing survey
of nearby galaxies searching for infrared (IR) transients with Spitzer/IRAC. We
present the discovery and follow-up observations of one of our most luminous
( mag, Vega) and red (
mag) transients, SPIRITS 15c. The transient was detected in a dusty spiral arm
of IC 2163 ( Mpc). Pre-discovery ground-based imaging revealed an
associated, shorter-duration transient in the optical and near-IR (NIR). NIR
spectroscopy showed a broad ( km s), double-peaked
emission line of He I at m, indicating an explosive origin. The NIR
spectrum of SPIRITS 15c is similar to that of the Type IIb SN 2011dh at a phase
of days. Assuming mag of extinction in SPIRITS 15c
provides a good match between their optical light curves. The IR light curves
and the extreme color cannot be explained using only a standard
extinction law. Another luminous ( mag) event, SPIRITS
14buu, was serendipitously discovered in the same galaxy. The source displays
an optical plateau lasting days, and we suggest a scenario similar
to the low-luminosity Type IIP SN 2005cs obscured by mag.
Other classes of IR-luminous transients can likely be ruled out in both cases.
If both events are indeed SNe, this may suggest of nearby
core-collapse SNe are missed by currently operating optical surveys.Comment: 19 pages, 7 Figures, 4 Table
A New Dark Matter Candidate: Non-thermal Sterile Neutrinos
We propose a new and unique dark matter candidate: eV to
keV sterile neutrinos produced via lepton number-driven resonant MSW
(Mikheyev-Smirnov-Wolfenstein) conversion of active neutrinos. The requisite
lepton number asymmetries in any of the active neutrino flavors range from
10 to 10 of the photon number - well within primordial
nucleosynthesis bounds. The unique feature here is that the adiabaticity
condition of the resonance strongly favors the production of lower energy
sterile neutrinos. The resulting non-thermal (cold) energy spectrum can cause
these sterile neutrinos to revert to non-relativistic kinematics at an early
epoch, so that free-streaming lengths at or below the dwarf galaxy scale are
possible. Therefore, the main problem associated with light neutrino dark
matter candidates can be circumvented in our model.Comment: Latex 11 pages + 1 figur
Confirmation of SBS 1150+599A As An Extremely Metal-Poor Planetary Nebula
SBS 1150+599A is a blue stellar object at high galactic latitude discovered
in the Second Byurakan Survey. New high-resolution images of SBS 1150+599A are
presented, demonstrating that it is very likely to be an old planetary nebula
in the galactic halo, as suggested by Tovmassian et al (2001). An H-alpha image
taken with the WIYN 3.5-m telescope and its "tip/tilt" module reveals the
diameter of the nebula to be 9.2", comparable to that estimated from spectra by
Tovmassian et al. Lower limits to the central star temperature were derived
using the Zanstra hydrogen and helium methods to determine that the star's
effective temperature must be > 68,000K and that the nebula is optically thin.
New spectra from the MMT and FLWO telescopes are presented, revealing the
presence of strong [Ne V] lambda 3425, indicating that the central star
temperature must be > 100,000K. With the revised diameter, new central star
temperature, and an improved central star luminosity, we can constrain
photoionization models for the nebula significantly better than before. Because
the emission-line data set is sparse, the models are still not conclusive.
Nevertheless, we confirm that this nebula is an extremely metal-poor planetary
nebula, having a value for O/H that is less than 1/100 solar, and possibly as
low as 1/500 solar.Comment: 19 pages, 6 figures. Accepted for publication in the Astronomical
Journa
Sustainability appraisal: Jack of all trades, master of none?
Sustainable development is a commonly quoted goal for decision making and supports a large number of other discourses. Sustainability appraisal has a stated goal of supporting decision making for sustainable development. We suggest that the inherent flexibility of sustainability appraisal facilitates outcomes that often do not adhere to the three goals enshrined in most definitions of sustainable development: economic growth, environmental protection and enhancement, and the wellbeing of the human population. Current practice is for sustainable development to be disenfranchised through the interpretation of sustainability, whereby the best alternative is good enough even when unsustainable. Practitioners must carefully and transparently review the frameworks applied during sustainability appraisal to ensure that outcomes will meet the three goals, rather than focusing on a discourse that emphasises one or more goals at the expense of the other(s)
Making Maps Of The Cosmic Microwave Background: The MAXIMA Example
This work describes Cosmic Microwave Background (CMB) data analysis
algorithms and their implementations, developed to produce a pixelized map of
the sky and a corresponding pixel-pixel noise correlation matrix from time
ordered data for a CMB mapping experiment. We discuss in turn algorithms for
estimating noise properties from the time ordered data, techniques for
manipulating the time ordered data, and a number of variants of the maximum
likelihood map-making procedure. We pay particular attention to issues
pertinent to real CMB data, and present ways of incorporating them within the
framework of maximum likelihood map-making. Making a map of the sky is shown to
be not only an intermediate step rendering an image of the sky, but also an
important diagnostic stage, when tests for and/or removal of systematic effects
can efficiently be performed. The case under study is the MAXIMA data set.
However, the methods discussed are expected to be applicable to the analysis of
other current and forthcoming CMB experiments.Comment: Replaced to match the published version, only minor change
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