1,826 research outputs found

    Constructing families of moderate-rank elliptic curves over number fields

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    We generalize a construction of families of moderate rank elliptic curves over Q\mathbb{Q} to number fields K/QK/\mathbb{Q}. The construction, originally due to Steven J. Miller, \'Alvaro Lozano-Robledo and Scott Arms, invokes a theorem of Rosen and Silverman to show that computing the rank of these curves can be done by controlling the average of the traces of Frobenius, the construction for number fields proceeds in essentially the same way. One novelty of this method is that we can construct families of moderate rank without having to explicitly determine points and calculating determinants of height matrices.Comment: Version 1.0, 4 pages, sequel to arXiv:math/040657

    Language discrimination by human newborns and by cotton-top tamarin monkeys

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    Humans, but no other animal, make meaningful use of spoken language. What is unclear, however, is whether this capacity depends on a unique constellation of perceptual and neurobiological mechanisms, or whether a subset of such mechanisms are shared with other organisms. To explore this problem, we conducted parallel experiments on human newborns and cotton-top tamarin monkeys to assess their ability to discriminate unfamiliar languages. Using a habituation-dishabituation procedure, we show that human newborns and tamarins can discriminate sentences from Dutch and Japanese, but not if the sentences are played backwards. Moreover, the cues for discrimination are not present in backward speech. This suggests that the human newborns' tuning to certain properties of speech relies on general processes of the primate auditory system

    Graphulo: Linear Algebra Graph Kernels for NoSQL Databases

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    Big data and the Internet of Things era continue to challenge computational systems. Several technology solutions such as NoSQL databases have been developed to deal with this challenge. In order to generate meaningful results from large datasets, analysts often use a graph representation which provides an intuitive way to work with the data. Graph vertices can represent users and events, and edges can represent the relationship between vertices. Graph algorithms are used to extract meaningful information from these very large graphs. At MIT, the Graphulo initiative is an effort to perform graph algorithms directly in NoSQL databases such as Apache Accumulo or SciDB, which have an inherently sparse data storage scheme. Sparse matrix operations have a history of efficient implementations and the Graph Basic Linear Algebra Subprogram (GraphBLAS) community has developed a set of key kernels that can be used to develop efficient linear algebra operations. However, in order to use the GraphBLAS kernels, it is important that common graph algorithms be recast using the linear algebra building blocks. In this article, we look at common classes of graph algorithms and recast them into linear algebra operations using the GraphBLAS building blocks.Comment: 10 page

    Clinically small tonsils are typically not obstructive in children during drug-induced sleep endoscopy

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    OBJECTIVE: To determine whether the degree of lateral pharyngeal wall (LPW) obstruction on pediatric drug-induced sleep endoscopy (DISE) correlates with preprocedure tonsillar hypertrophy score on physical examination, and to determine if clinically small tonsils are obstructive. METHODS: Retrospective review of 154 patients who underwent DISE at a single pediatric tertiary care center over a 4-year period. Inclusion criteria were documentation of Brodsky tonsil score on preoperative physical examination. Exclusion criteria were previous tonsillectomy, adenoidectomy, or adenotonsillectomy. Lateral pharyngeal wall obstruction was graded for each patient from 0 (no obstruction) to 3 (severe obstruction) using a validated pediatric DISE scoring system known as the Chan-Parikh scoring system (C-P). Data were analyzed using multivariate linear regression controlling for age at time of DISE and presence of comorbid conditions. RESULTS: One hundred fifteen patients met criteria for analysis. Median age at DISE was 5.1 years. A moderate positive correlation was calculated between Brodsky score and DISE score, Spearman correlation coefficient 0.55, P = 50% obstruction); and six (9%) had a score of 3 (100% obstruction). CONCLUSION: There is a positive correlation between Brodsky Score and DISE LPW score. The majority of children with sleep-disordered breathing with a Brodsky score of 1 did not demonstrate LPW obstruction. These children may benefit from DISE for identification of alternative sites of upper airway obstructio

    Accurate cell tracking and lineage construction in live-cell imaging experiments with deep learning

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    Live-cell imaging experiments have opened an exciting window into the behavior of living systems. While these experiments can produce rich data, the computational analysis of these datasets is challenging. Single-cell analysis requires that cells be accurately identified in each image and subsequently tracked over time. Increasingly, deep learning is being used to interpret microscopy image with single cell resolution. In this work, we apply deep learning to the problem of tracking single cells in live-cell imaging data. Using crowdsourcing and a human-in-the-loop approach to data annotation, we constructed a dataset of over 11,000 trajectories of cell nuclei that includes lineage information. Using this dataset, we successfully trained a deep learning model to perform cell tracking within a linear programming framework. Benchmarking tests demonstrate that our method achieves state-of-the-art performance on the task of cell tracking with respect to multiple accuracy metrics. Further, we show that our deep learning-based method generalizes to perform cell tracking for both fluorescent and brightfield images of the cell cytoplasm, despite having never been trained those data types. This enables analysis of live-cell imaging data collected across imaging modalities. A persistent cloud deployment of our cell tracker is available at http://www.deepcell.org

    Acute tear of the fascia cruris at the attachment to the Achilles tendon: a new diagnosis

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    BACKGROUND: The fascia cruris encloses the posterior structures of the calf and connects to the paratenon and the Achilles tendon. We describe the clinical presentation, ultrasound imaging characteristics and the time to the recovery of tears of the fascia cruris at the attachment to the Achilles tendon. METHODS: Retrospective review of 11 tears of the fascia cruris in the different legs as separate events in 9 patients (6 male and 3 female, mean age 35.52 years, range 11–48) identified using diagnostic ultrasound, after presenting with Achillodynia. RESULTS: 11 participants presented at a mean of 4.5 weeks (range 0.5–12) after onset of symptoms. The left Achilles was more commonly injured than the right (7 : 4) and the lateral side more than the medial (6 : 4) with one case with medial and lateral presentation. Clinically, there was swelling and tenderness over the medial or lateral border in the mid to upper portion of the Achilles. 7 of the 11 (63.6%) had functional overpronation. Ultrasound appearances of a tear were identified as hypoechoic area extending from the medial or lateral border of the Achilles extending along the anatomical plane of the fascia cruris. Average return to activity was 5.2 weeks (range 1–22). Participants presenting later had longer recovery but all participants returned to full activity (r=0.4). CONCLUSIONS: This is the first description of the clinical details and sonographic findings of a tear to the fascia cruris at its attachment to the Achilles tendon. This needs to be considered as a cause of Achillodynia in athletes as recognition will affect the management

    Adaptation Space: Surviving Non-Maskable Failures

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    Some failures cannot be masked by redundancies, because an unanticipated situation occurred, because fault-tolerance measures were not adequate, or because there was a security breach (which is not amenable to replication). Applications that wish to continue to offer some service despite nonmaskable failure must adapt to the loss of resources. When numerous combinations of non-maskable failure modes are considered, the set of possible adaptations becomes complex. This paper presents adaptation spaces, a formalism for navigating among combinations of adaptations. An adaptation space describes a collection of possible adaptations of a software component or system, and provides a uniform way of viewing a group of alternative software adaptations. Adaptation spaces describe the different means for monitoring the conditions that different adaptations depend on, and the particular configurations through which an adaptive application navigate. Our goal is to use adaptation spaces to provide survivable services to applications despite non-maskable failures such as malicious attacks. We present the basic concepts concerning adaptation spaces, with examples. We then present a formal model for reasoning about and selecting alternative adaptations, allowing developers of survivable application to automate their system’s adaptive behavior

    Principal variables analysis for non-Gaussian data

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    Principal variables analysis (PVA) is a technique for selecting a subset of variables that capture as much of the information in a dataset as possible. Existing approaches for PVA are based on the Pearson correlation matrix, which is not well-suited to describing the relationships between non-Gaussian variables. We propose a generalized approach to PVA enabling the use of different types of correlation, and we explore using Spearman, Gaussian copula, and polychoric correlations as alternatives to Pearson correlation when performing PVA. We compare performance in simulation studies varying the form of the true multivariate distribution over a wide range of possibilities. Our results show that on continuous non-Gaussian data, using generalized PVA with Gaussian copula or Spearman correlations provides a major improvement in performance compared to Pearson. Meanwhile, on ordinal data, generalized PVA with polychoric correlations outperforms the rest by a wide margin. We apply generalized PVA to a dataset of 102 clinical variables measured on individuals with X-linked dystonia parkinsonism (XDP), a rare neurodegenerative disorder, and we find that using different types of correlation yields substantively different sets of principal variables

    Therapeutic Phlebotomy Related to Polycythemia Vera and Hemochromatosis

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    This study looks at therapeutic phlebotomy as first-line treatment of blood disorders, including polycythemia vera and hemochromatosis. Some professionals prefer alternative treatments to phlebotomy
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