941 research outputs found
The ultra-compact binary candidate KUV 23182+1007 is a bright quasar
KUV 23182+1007 was identified as a blue object in the Kiso UV Survey in the
1980s. Classification-dispersion spectroscopy showed a featureless continuum
except for a strong emission line in the region of He II 4686 A. This is a
hallmark of the rare AM CVn class of cataclysmic variable star, so we have
obtained a high-S/N blue spectrum of this object to check its classification.
Instead, the spectrum shows a strong quasar-like emission line centred on 4662
A. Comparison with the SDSS quasar template spectra confirms that KUV
23182+1007 is a quasar with a redshift of z = 0.665.Comment: 4 pages, 2 figures, to appear in IBVS. Data are available from
http://www.astro.keele.ac.uk/~jkt
The Acquisition of a Plastid by Haptophytes, Cryptophytes, and Photosynthetic Heterokonts
Red algae and green plants are known to have obtained their photosynthetic organelles, or plastids, through the endosymbiotic adoption of cyanobacteria. It is still widely debated as to how other eukaryotic alga such as haptophytes, cryptophytes, and photosynthetic heterokonts obtained their plastids, although all are believed to be descended from a red alga. In this thesis, genome-level regressions, analyses of residuals, and Fisher's exact tests were used to determine how these three eukaryotic algal groups obtained their plastids. A phylogeny also was constructed using 11 plastid genes from various red algae, green plants, haptophytes, cryptophytes, and photosynthetic heterokonts. The results from these collective analyses indicate that multiple endosymbiosis events occurred. Furthermore, they show that a plastid was passed from a red alga, first to cryptophytes, then to photosynthetic heterokonts, and finally to haptophytes in a series of endosymbioses.  M.S
Utilization of Dantrolene in Stiff-Person Syndrome: A Case Report
Setting: University hospital-based acute rehabilitation.
Patient: 75-year-old woman with Stiff-Person Syndrome (SPS) with a recent fall and Colles fracture.
Case Description: Four months prior to admission, the patient was diagnosed with SPS, negative for anti-GAD antibodies. Diagnosis was based on a 3-year history of progressive rigidity leading to frequent falls and fractures. Anxiety and fear of falling limited her mobility, and she sustained a sacral pressure ulcer during acute hospitalization. On admission, history was remarkable for unsteady gait and muscle cramps exacerbated when startled or excited. Examination was remarkable for rigidity in her axial and limb muscles. She presented at the maximal assist level for transfers and toileting and moderate assist level for grooming and ambulation using a platform walker (right arm in cast). She was unable to tolerate titration of diazepam due to sedation, or baclofen due to hypotension.
Results: During acute rehabilitation, rigidity was treated with titration of dantrolene (from 25 to 50 mg four times daily) in addition to maximal tolerated doses of diazepam (1 mg qAM/2 mg qPM) and baclofen (20mg TID). The addition of dantrolene reduced rigidity and improved range of motion, both subjectively per patient and objectively by exam. Functional gains stalled with dose decrease and resumed with dose increase. She had pronounced gains in grooming to the supervision level, modest gains in transfers and toileting to the moderate assist level, but remained at the moderate assist level for ambulation. Progress was limited due to a change to non-weight bearing status of her right arm. Anxiety and depression were improved with buspirone, paroxetine, and psychological counseling.
Discussion: SPS results in significant activity of daily life and ambulatory dysfunction as exemplified by her pressure ulcer and multiple falls. Although GABA agonists are the preferred treatment for SPS, the adverse effects of high doses can increase the risk of falls. Dantrolene reduced muscle rigidity and improved function without sedative or hypotensive effects.
Conclusion: Dantrolene is a useful additional treatment for SPS rigidity
Blockade of Interferon Beta, but Not Interferon Alpha, Signaling Controls Persistent Viral Infection
SummaryAlthough type I interferon (IFN-I) is thought to be beneficial against microbial infections, persistent viral infections are characterized by high interferon signatures suggesting that IFN-I signaling may promote disease pathogenesis. During persistent lymphocytic choriomeningitis virus (LCMV) infection, IFNα and IFNβ are highly induced early after infection, and blocking IFN-I receptor (IFNAR) signaling promotes virus clearance. We assessed the specific roles of IFNβ versus IFNα in controlling LCMV infection. While blockade of IFNβ alone does not alter early viral dissemination, it is important in determining lymphoid structure, lymphocyte migration, and anti-viral T cell responses that lead to accelerated virus clearance, approximating what occurs during attenuation of IFNAR signaling. Comparatively, blockade of IFNα was not associated with improved viral control, but with early dissemination of virus. Thus, despite their use of the same receptor, IFNβ and IFNα have unique and distinguishable biologic functions, with IFNβ being mainly responsible for promoting viral persistence
Connectionist natural language parsing
The key developments of two decades of connectionist parsing are reviewed. Connectionist parsers are assessed according to their ability to learn to represent syntactic structures from examples automatically, without being presented with symbolic grammar rules. This review also considers the extent to which connectionist parsers offer computational models of human sentence processing and provide plausible accounts of psycholinguistic data. In considering these issues, special attention is paid to the level of realism, the nature of the modularity, and the type of processing that is to be found in a wide range of parsers
The RNA Binding Protein Quaking Regulates Formation of circRNAs
SummaryCircular RNAs (circRNAs), formed by non-sequential back-splicing of pre-mRNA transcripts, are a widespread form of non-coding RNA in animal cells. However, it is unclear whether the majority of circRNAs represent splicing by-products without function or are produced in a regulated manner to carry out specific cellular functions. We show that hundreds of circRNAs are regulated during human epithelial-mesenchymal transition (EMT) and find that the production of over one-third of abundant circRNAs is dynamically regulated by the alternative splicing factor, Quaking (QKI), which itself is regulated during EMT. Furthermore, by modulating QKI levels, we show the effect on circRNA abundance is dependent on intronic QKI binding motifs. Critically, the addition of QKI motifs is sufficient to induce de novo circRNA formation from transcripts that are normally linearly spliced. These findings demonstrate circRNAs are both purposefully synthesized and regulated by cell-type specific mechanisms, suggesting they play specific biological roles in EMT
An Invitation to Higher Gauge Theory
In this easy introduction to higher gauge theory, we describe parallel
transport for particles and strings in terms of 2-connections on 2-bundles.
Just as ordinary gauge theory involves a gauge group, this generalization
involves a gauge '2-group'. We focus on 6 examples. First, every abelian Lie
group gives a Lie 2-group; the case of U(1) yields the theory of U(1) gerbes,
which play an important role in string theory and multisymplectic geometry.
Second, every group representation gives a Lie 2-group; the representation of
the Lorentz group on 4d Minkowski spacetime gives the Poincar\'e 2-group, which
leads to a spin foam model for Minkowski spacetime. Third, taking the adjoint
representation of any Lie group on its own Lie algebra gives a 'tangent
2-group', which serves as a gauge 2-group in 4d BF theory, which has
topological gravity as a special case. Fourth, every Lie group has an 'inner
automorphism 2-group', which serves as the gauge group in 4d BF theory with
cosmological constant term. Fifth, every Lie group has an 'automorphism
2-group', which plays an important role in the theory of nonabelian gerbes. And
sixth, every compact simple Lie group gives a 'string 2-group'. We also touch
upon higher structures such as the 'gravity 3-group' and the Lie 3-superalgebra
that governs 11-dimensional supergravity.Comment: 60 pages, based on lectures at the 2nd School and Workshop on Quantum
Gravity and Quantum Geometry at the 2009 Corfu Summer Institut
Cognitive Information Processing
Contains reports on four research projects.National Science Foundation (Grant SED76-81985)Associated Press (Grant)Providence Gravure, Inc. (Grant)Taylor Publishing Company (Grant
- …