917 research outputs found
Genome-wide DNA hypomethylation and RNA:DNA hybrid accumulation in Aicardi-Goutières syndrome.
Aicardi-Goutières syndrome (AGS) is a severe childhood inflammatory disorder that shows clinical and genetic overlap with systemic lupus erythematosus (SLE). AGS is thought to arise from the accumulation of incompletely metabolized endogenous nucleic acid species owing to mutations in nucleic acid-degrading enzymes TREX1 (AGS1), RNase H2 (AGS2, 3 and 4), and SAMHD1 (AGS5). However, the identity and source of such immunogenic nucleic acid species remain undefined. Using genome-wide approaches, we show that fibroblasts from AGS patients with AGS1-5 mutations are burdened by excessive loads of RNA:DNA hybrids. Using MethylC-seq, we show that AGS fibroblasts display pronounced and global loss of DNA methylation and demonstrate that AGS-specific RNA:DNA hybrids often occur within DNA hypomethylated regions. Altogether, our data suggest that RNA:DNA hybrids may represent a common immunogenic form of nucleic acids in AGS and provide the first evidence of epigenetic perturbations in AGS, furthering the links between AGS and SLE
Identifying Destination Image of Rural Areas: The Case of Brookings, South Dakota
A clear understanding of destination image is crucial for developing effective marketing and positioning strategies. The purpose of the study is to examine the images of Brookings perceived by actual tourists. An online questionnaire was developed and sent to email subscribers of the largest local event center. A total of 344 valid responses were received. Overall tourists had positive perceptions of Brookings as a tourism destination. The study identified six Brookings’ image dimensions, including Outdoor Activities and Natural Scenery, Atmosphere, Tourism Infrastructure, Value for Money and Convenience, Historic Attractions, and College Town Style. The social and cultural environment is the most favored element in Brookings. As a college town, Brookings was differentiated from other rural tourism destinations. It is suggested that the city and the university work in partnership to increase visitation both to the campus and the community. To enhance Brookings’ image, destination marketers should focus on the low-rated image items and incorporate them in destination marketing materials
A Census of Outflow to Magnetic Field Orientations in Nearby Molecular Clouds
We define a sample of 200 protostellar outflows showing blue and redshifted
CO emission in the nearby molecular clouds Ophiuchus, Taurus, Perseus and Orion
to investigate the correlation between outflow orientations and local, but
relatively large-scale, magnetic field directions traced by Planck 353 GHz dust
polarization. At high significance (p~1e-4), we exclude a random distribution
of relative orientations and find that there is a preference for alignment of
projected plane of sky outflow axes with magnetic field directions. The
distribution of relative position angles peaks at ~30deg and exhibits a broad
dispersion of ~50deg. These results indicate that magnetic fields have
dynamical influence in regulating the launching and/or propagation directions
of outflows. However, the significant dispersion around perfect alignment
orientation implies that there are large measurement uncertainties and/or a
high degree of intrinsic variation caused by other physical processes, such as
turbulence or strong stellar dynamical interactions. Outflow to magnetic field
alignment is expected to lead to a correlation in the directions of nearby
outflow pairs, depending on the degree of order of the field. Analyzing this
effect we find limited correlation, except on relatively small scales < 0.5 pc.
Furthermore, we train a convolutional neural network to infer the inclination
angle of outflows with respect to the line of sight and apply it to our outflow
sample to estimate their full 3D orientations. We find that the angles between
outflow pairs in 3D space also show evidence of small-scale alignment.Comment: ApJ Accepte
How good are Global Newton methods? Part 2
Newton's method applied to certain problems with a discontinuous derivative operator is shown to be effective. A global Newton method in this setting is exhibited and its computational complexity is estimated. As an application a method is proposed to solve problems of linear inequalities (linear programming, phase 1). Using an example of the Klee-Minty type due to Blair, it was found that the simplex method (used in super-lindo) required over 2,000 iterations, while the method above required an average of 8 iterations (Newton steps) over 15 random starting values.Naval Surface Weapons Center, Dahlgren, VAhttp://archive.org/details/howgoodareglobal00goldO&MN Direct FundingApproved for public release; distribution is unlimited
A Quantitative Approach to Understand Self-Supervised Models as Cross-lingual Feature Extractors
In this work, we study the features extracted by English self-supervised
learning (SSL) models in cross-lingual contexts and propose a new metric to
predict the quality of feature representations. Using automatic speech
recognition (ASR) as a downstream task, we analyze the effect of model size,
training objectives, and model architecture on the models' performance as a
feature extractor for a set of topologically diverse corpora. We develop a
novel metric, the Phonetic-Syntax Ratio (PSR), to measure the phonetic and
synthetic information in the extracted representations using deep generalized
canonical correlation analysis. Results show the contrastive loss in the
wav2vec2.0 objective facilitates more effective cross-lingual feature
extraction. There is a positive correlation between PSR scores and ASR
performance, suggesting that phonetic information extracted by monolingual SSL
models can be used for downstream tasks in cross-lingual settings. The proposed
metric is an effective indicator of the quality of the representations and can
be useful for model selection.Comment: 12 pages, 5 figures, 4 table
Condensing Multilingual Knowledge with Lightweight Language-Specific Modules
Incorporating language-specific (LS) modules is a proven method to boost
performance in multilingual machine translation. This approach bears similarity
to Mixture-of-Experts (MoE) because it does not inflate FLOPs. However, the
scalability of this approach to hundreds of languages (experts) tends to be
unmanageable due to the prohibitive number of parameters introduced by
full-rank matrices in fully-connected layers. In this work, we introduce the
Language-Specific Matrix Synthesis (LMS) method. This approach constructs LS
modules by generating low-rank matrices from two significantly smaller matrices
to approximate the full-rank matrix. Furthermore, we condense multilingual
knowledge from multiple LS modules into a single shared module with the Fuse
Distillation (FD) technique to improve the efficiency of inference and model
serialization. We show that our LMS method significantly outperforms previous
LS methods and MoE methods with the same amount of extra parameters, e.g., 1.73
BLEU points over the Switch Transformer on many-to-many multilingual machine
translation. Importantly, LMS is able to have comparable translation
performance with much fewer parameters.Comment: Accepted at the main conference of EMNLP 202
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