1,158 research outputs found

    AMPA experimental communications systems

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    The program was conducted to demonstrate the satellite communication advantages of Adaptive Phased Array Technology. A laboratory based experiment was designed and implemented to demonstrate a low earth orbit satellite communications system. Using a 32 element, L-band phased array augmented with 4 sets of weights (2 for reception and 2 for transmission) a high speed digital processing system and operating against multiple user terminals and interferers, the AMPA system demonstrated: communications with austere user terminals, frequency reuse, communications in the face of interference, and geolocation. The program and experiment objectives are described, the system hardware and software/firmware are defined, and the test performed and the resultant test data are presented

    Metaphoric coherence: Distinguishing verbal metaphor from `anomaly\u27

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    Theories and computational models of metaphor comprehension generally circumvent the question of metaphor versus “anomaly” in favor of a treatment of metaphor versus literal language. Making the distinction between metaphoric and “anomalous” expressions is subject to wide variation in judgment, yet humans agree that some potentially metaphoric expressions are much more comprehensible than others. In the context of a program which interprets simple isolated sentences that are potential instances of cross‐modal and other verbal metaphor, I consider some possible coherence criteria which must be satisfied for an expression to be “conceivable” metaphorically. Metaphoric constraints on object nominals are represented as abstracted or extended along with the invariant structural components of the verb meaning in a metaphor. This approach distinguishes what is preserved in metaphoric extension from that which is “violated”, thus referring to both “similarity” and “dissimilarity” views of metaphor. The role and potential limits of represented abstracted properties and constraints is discussed as they relate to the recognition of incoherent semantic combinations and the rejection or adjustment of metaphoric interpretations

    Adaptive multibeam phased array design for a Spacelab experiment

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    The parametric tradeoff analyses and design for an Adaptive Multibeam Phased Array (AMPA) for a Spacelab experiment are described. This AMPA Experiment System was designed with particular emphasis to maximize channel capacity and minimize implementation and cost impacts for future austere maritime and aeronautical users, operating with a low gain hemispherical coverage antenna element, low effective radiated power, and low antenna gain-to-system noise temperature ratio

    Laparoscopic Resection of a Small Bowel Lipoma with Incidental Intussusception

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    Small bowel lipomas, which can cause intussusception and gastrointestinal bleeding, can be managed with laparoscopic resection when diagnosed preoperatively

    An evaluation of multiaxial fatigue criteria for welded joints under proportional load based on the notch stress, structural stress and nominal stress approach

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    Currently, there exists a relatively large number of guidelines and recommendations which deal with the fatigue assessment of welded structures. In these guidelines, different approaches are proposed to assess the service life of welded structures under multi-axial loading conditions. Aim of this paper is the evaluation of the quality of these approaches. Experimental fatigue data using multiaxial loading conditions from the literature were collected establishing a target data set. An evaluation of the data was performed using three guidelines (IIW-recommendations, FKM guideline and Eurocode 3) as well as a critical plane approach. All evaluations have been performed for the nominal, the structural and the effective notch stress approach

    Memory Functioning for Personally Experienced and Witnessed Events in Children with Autism and the Implications for Educators, Mental Health Professionals, and the Law

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    Several researchers have hypothesized a deficit in memory processing to exist in children with a diagnosis of autism spectrum disorder (ASD). This hypothesis has been supported by findings of deficient recall and recognition ability in children with ASD. Specifically, research has pointed to greater deficits in their ability to recall events related to the self as opposed to others. However, such research has not explored how memory functioning would be impacted when an event with an emotional tenor was used and when a forced choice yes/no paradigm was used to extricate what was remembered from the event. The current study aimed to compare recognition memory for personally experienced and witnessed events using a mock stranger-danger scenario. Forty-two children with ASD underwent either a personally experienced or witnessed event. Following the event, the child was administered a survey assessing their recognition of both thematic and detailed content from the event. No statistically significant differences were identified for recognition memory between the personally experienced and witnessed events. While differences between the groups were not found to be significant, it was revealed that there was a trend towards significance for better recognition of details for the witnessed than for the personally experienced event. Implications for future research are discussed as well as the potential impact of such findings in the terms of forensic and educational domains

    A label-free differential quantitative mass spectrometry method for the characterization and identification of protein changes during citrus fruit development

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    <p>Abstract</p> <p>Background</p> <p>Citrus is one of the most important and widely grown commodity fruit crops. In this study a label-free LC-MS/MS based shot-gun proteomics approach was taken to explore three main stages of citrus fruit development. These approaches were used to identify and evaluate changes occurring in juice sac cells in various metabolic pathways affecting citrus fruit development and quality.</p> <p>Results</p> <p>Protein changes in citrus juice sac cells were identified and quantified using label-free shotgun methodologies. Two alternative methods, differential mass-spectrometry (dMS) and spectral counting (SC) were used to analyze protein changes occurring during earlier and late stages of fruit development. Both methods were compared in order to develop a proteomics workflow that could be used in a non-model plant lacking a sequenced genome. In order to resolve the bioinformatics limitations of EST databases from species that lack a full sequenced genome, we established iCitrus. iCitrus is a comprehensive sequence database created by merging three major sources of sequences (HarvEST:citrus, NCBI/citrus/unigenes, NCBI/citrus/proteins) and improving the annotation of existing unigenes. iCitrus provided a useful bioinformatics tool for the high-throughput identification of citrus proteins. We have identified approximately 1500 citrus proteins expressed in fruit juice sac cells and quantified the changes of their expression during fruit development. Our results showed that both dMS and SC provided significant information on protein changes, with dMS providing a higher accuracy.</p> <p>Conclusion</p> <p>Our data supports the notion of the complementary use of dMS and SC for label-free comparative proteomics, broadening the identification spectrum and strengthening the identification of trends in protein expression changes during the particular processes being compared.</p

    Genome-Scale Analysis of Programmed DNA Elimination Sites in Tetrahymena thermophila

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    Genetically programmed DNA rearrangements can regulate mRNA expression at an individual locus or, for some organisms, on a genome-wide scale. Ciliates rely on a remarkable process of whole-genome remodeling by DNA elimination to differentiate an expressed macronucleus (MAC) from a copy of the germline micronucleus (MIC) in each cycle of sexual reproduction. Here we describe results from the first high-throughput sequencing effort to investigate ciliate genome restructuring, comparing Sanger long-read sequences from a Tetrahymena thermophila MIC genome library to the MAC genome assembly. With almost 25% coverage of the unique-sequence MAC genome by MIC genome sequence reads, we created a resource for positional analysis of MIC-specific DNA removal that pinpoints MAC genome sites of DNA elimination at nucleotide resolution. The widespread distribution of internal eliminated sequences (IES) in promoter regions and introns suggests that MAC genome restructuring is essential not only for what it removes (for example, active transposons) but also for what it creates (for example, splicing-competent introns). Consistent with the heterogeneous boundaries and epigenetically modulated efficiency of individual IES deletions studied to date, we find that IES sites are dramatically under-represented in the ∼25% of the MAC genome encoding exons. As an exception to this general rule, we discovered a previously unknown class of small (<500 bp) IES with precise elimination boundaries that can contribute the 3′ exon of an mRNA expressed during genome restructuring, providing a new mechanism for expanding mRNA complexity in a developmentally regulated manner
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