496 research outputs found

    Evaluation of modern hydrogen masers

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    The masers were tested for environmental sensitivities (magnetic field, temperature, barometric pressure) and long-term aging. Allan variance runs of 72 days were made in order to attain averaging times from several seconds to 1 million seconds. Auto- and cross-correlation techniques were used to determine the effects of uncontrolled parameters such as humidity. Three-cornered-hat and other data reduction techniques were used to determine the characteristics of the individual masers

    Ontology-Based Production Simulation with OntologySim

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    Imagine the possibility to save a simulation at any time, modify or analyze it, and restart again with exactly the same state. The conceptualization and its concrete manifestation in the implementation OntologySim is demonstrated in this paper. The presented approach of a fully ontology-based simulation can solve current challenges in modeling and simulation in production science. Due to the individualization and customization of products and the resulting increase in complexity of production, a need for flexibly adaptable simulations arises. This need is exemplified in the trend towards Digital Twins and Digital Shadows. Their application to production systems, against the background of an ever increasing speed of change in such systems, is arduous. Moreover, missing understandability and human interpretability of current approaches hinders successful, goal oriented applications. The OntologySim can help solving this challenge by providing the ability to generate truly cyber physical systems, both interlocked with reality and providing a simulation framework. In a nutshell, this paper presents a discrete-event-based open-source simulation using multi-agency and ontology

    Prediction of bed load transport on small gravel-bed streams

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    Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732Rates and size distributions of bed load were calculated using 3 transport relations and compared to data collected on three streams with sand-gravel beds in the Goodwin Creek Experimental Watershed in north central Mississippi, USA. Bed load transport rates were greatly over predicted by two of the three relations with the third yielding values closer to the measured values. Predictions of the median size of the bed load as compared to measured values were within about 100 percent for all three relations. The effect of bed material size distributions on the predicted rates from the 3 relations was evaluated and it was found that bed material sizes substantially larger than those measured in the field were needed to yield predicted rates close to those measured in the field for two of the three relations. The third relation yielded transport rates within about 50 percent of the measured rates using the measured bed material surface size distribution as input

    Exclusion of the Locus for Autosomal Recessive Pseudohypoaldosteronism Type 1 from the Mineralocorticoid Receptor Gene Region on Human Chromosome 4q by Linkage Analysis.

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    Pseudohypoaldosteronism type 1 (PHA1) is an uncommon inherited disorder characterized by salt-wasting in infancy arising from target organ unresponsiveness to mineralocorticoids. Clinical expression of the disease varies from severely affected infants who may die to apparently asymptomatic individuals. Inheritance is Mendelian and may be either autosomal dominant or autosomal recessive. A defect in the mineralocorticoid receptor has been implicated as a likely cause of PHA1. The gene for human mineralocorticoid receptor (MLR) has been cloned and physically mapped to human chromosome 4q31.1-31.2. The etiological role of MLR in autosomal recessive PHA1 was investigated by performing linkage analysis between PHA1 and three simple sequence length polymorphisms (D4S192, D4S1548, and D4S413) on chromosome 4q in 10 consanguineous families. Linkage analysis was carried out assuming autosomal recessive inheritance with full penetrance and zero phenocopy rate using the MLINK program for two-point analysis and the HOMOZ program for multipoint analysis. Lod scores of less than -2 were obtained over the whole region from D4S192 to D4S413 encompassing MLR. This provdes evidence against MLR as the site of mutations causing PHA1 in the majority of autosomal recessive families

    Designing an adaptive production control system using reinforcement learning

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    Modern production systems face enormous challenges due to rising customer requirements resulting in complex production systems. The operational efficiency in the competitive industry is ensured by an adequate production control system that manages all operations in order to optimize key performance indicators. Currently, control systems are mostly based on static and model-based heuristics, requiring significant human domain knowledge and, hence, do not match the dynamic environment of manufacturing companies. Data-driven reinforcement learning (RL) showed compelling results in applications such as board and computer games as well as first production applications. This paper addresses the design of RL to create an adaptive production control system by the real-world example of order dispatching in a complex job shop. As RL algorithms are “black box” approaches, they inherently prohibit a comprehensive understanding. Furthermore, the experience with advanced RL algorithms is still limited to single successful applications, which limits the transferability of results. In this paper, we examine the performance of the state, action, and reward function RL design. When analyzing the results, we identify robust RL designs. This makes RL an advantageous control system for highly dynamic and complex production systems, mainly when domain knowledge is limited

    Crossover from 2D to 3D in a weakly interacting Fermi gas

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    We have studied the transition from two to three dimensions in a low temperature weakly interacting 6^6Li Fermi gas. Below a critical atom number, N2DN_{2D}, only the lowest transverse vibrational state of a highly anisotropic oblate trapping potential is occupied and the gas is two-dimensional. Above N2DN_{2D} the Fermi gas enters the quasi-2D regime where shell structure associated with the filling of individual transverse oscillator states is apparent. This dimensional crossover is demonstrated through measurements of the cloud size and aspect ratio versus atom number.Comment: Replaced with published manuscrip

    Matching Reads to Many Genomes with the r-Index

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    The r-index is a tool for compressed indexing of genomic databases for exact pattern matching, which can be used to completely align reads that perfectly match some part of a genome in the database or to find seeds for reads that do not. This article shows how to download and install the programs ri-buildfasta and ri-align; how to call ri-buildfasta on an FASTA file to build an r-index for that file; and how to query that index with ri-align

    Efficient Construction of a Complete Index for Pan-Genomics Read Alignment

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    While short read aligners, which predominantly use the FM-index, are able to easily index one or a few human genomes, they do not scale well to indexing databases containing thousands of genomes. To understand why, it helps to examine the main components of the FM-index in more detail, which is a rank data structure over the Burrows-Wheeler Transform () of the string that will allow us to find the interval in the string\u2019s suffix array () containing pointers to starting positions of occurrences of a given pattern; second, a sample of the that\u2014when used with the rank data structure\u2014allows us access to the . The rank data structure can be kept small even for large genomic databases, by run-length compressing the , but until recently there was no means known to keep the sample small without greatly slowing down access to the . Now that Gagie et al. (SODA 2018) have defined an sample that takes about the same space as the run-length compressed \u2014we have the design for efficient FM-indexes of genomic databases but are faced with the problem of building them. In 2018 we showed how to build the of large genomic databases efficiently (WABI 2018) but the problem of building Gagie et al.\u2019s sample efficiently was left open. We compare our approach to state-of-the-art methods for constructing the sample, and demonstrate that it is the fastest and most space-efficient method on highly repetitive genomic databases. Lastly, we apply our method for indexing partial and whole human genomes and show that it improves over Bowtie with respect to both memory and time

    Prefix-free parsing for building big BWTs

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    High-throughput sequencing technologies have led to explosive growth of genomic databases; one of which will soon reach hundreds of terabytes. For many applications we want to build and store indexes of these databases but constructing such indexes is a challenge. Fortunately, many of these genomic databases are highly-repetitive - a characteristic that can be exploited to ease the computation of the Burrows-Wheeler Transform (BWT), which underlies many popular indexes. In this paper, we introduce a preprocessing algorithm, referred to as prefix-free parsing, that takes a text T as input, and in one-pass generates a dictionary D and a parse P of T with the property that the BWT of T can be constructed from D and P using workspace proportional to their total size and O(|T|)-time. Our experiments show that D and P are significantly smaller than T in practice, and thus, can fit in a reasonable internal memory even when T is very large. In particular, we show that with prefix-free parsing we can build an 131-MB run-length compressed FM-index (restricted to support only counting and not locating) for 1000 copies of human chromosome 19 in 2 h using 21 GB of memory, suggesting that we can build a 6.73 GB index for 1000 complete human-genome haplotypes in approximately 102 h using about 1 TB of memory
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