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Sample records for extrachromosomal circles structurally

  1. Formation of extrachromosomal circles from telomeric DNA in Xenopus laevis.

    PubMed

    Cohen, Sarit; Méchali, Marcel

    2002-12-01

    Instability and plasticity of telomeric DNA, which includes extrachromosomal DNA, are usually correlated with the absence of telomerase and with abnormal growth of mammalian cells. Here, we show the formation of extrachromosomal circular DNA of telomeric repeats (tel-eccDNA) during the development of Xenopus laevis. Tel-eccDNA is double-stranded relaxed circles composed of the vertebrate consensus telomeric repeats [TTAGGG](n). Its size varies from <2 to >20 kb and it comprises up to 10% of the total cellular telomere content of the early embryo (pre-MBT stage). The amount of tel-eccDNA is reduced in later developmental stages and in adult tissues. Using a cell-free system derived from Xenopus egg extracts, we show that tel-eccDNA can be formed de novo from the telomere chromosomal tracts of sperm nuclei and naked DNA in a replication-independent manner. These results reveal an unusual plasticity of telomeric DNA during normal development of Xenopus. PMID:12446568

  2. Amplified DNAs in laboratory stocks of Leishmania tarentolae: extrachromosomal circles structurally and functionally similar to the inverted-H-region amplification of methotrexate-resistant Leishmania major

    SciTech Connect

    Petrillo-Peixoto, M.L.; Beverley, S.M. )

    1988-12-01

    We describe the structure of amplified DNA that was discovered in two laboratory stocks of the protozoan parasite Leishmania tarentolae. Restriction mapping and molecular cloning revealed that a region of 42 kilobases was amplified 8- to 30-fold in these lines. Southern blot analyses of digested DNAs or chromosomes separated by pulsed-field electrophoresis showed that the amplified DNA corresponded to the H region, a locus defined originally by its amplification in methotrexate-resistant Leishmania major. Similarities between the amplified DNA of the two species included (i) extensive cross-hybridization; (ii) approximate conservation of sequence order; (iii) extrachromosomal localization; (iv) an overall inverted, head-to-head configuration as a circular 140-kilobase tetrameric molecule; (v) two regions of DNA sequence rearrangement, each of which was closely associated with the two centers of the inverted repeats; (vi) association with methotrexate resistance; and (vii) phenotypically conservative amplification, in which the wild-type chromosomal arrangement was retained without apparent modification. Our data showed that amplified DNA mediating drug resistance arose in unselected L. tarentolae, although the pressures leading to apparently spontaneous amplification and maintenance of the H region are not known. The simple structure and limited extent of DNA amplified in these and other Leishmania lines suggests that the study of gene amplification in Leishmania spp. offers an attractive model system for the study of amplification in cultured mammalian cells and tumors. We also introduced a method for measuring the size of large circular DNAs, using gamma-irradiation to introduce limited double-strand breaks followed by sizing of the linear DNAs by pulsed-field electrophoresis.

  3. Identification of extrachromosomal circular DNA in hop via rolling circle amplification

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During a survey looking for viruses affecting hop plants in the Willamette Valley of Oregon, a circular DNA molecule was identified via rolling circle amplification (RCA) and later characterized. The 5.7 kb long molecule only matched in a minor cover to a microsatellite region in the Humulus lupulus...

  4. Archaeal Extrachromosomal Genetic Elements

    PubMed Central

    Wang, Haina; Peng, Nan; Shah, Shiraz A.

    2015-01-01

    SUMMARY Research on archaeal extrachromosomal genetic elements (ECEs) has progressed rapidly in the past decade. To date, over 60 archaeal viruses and 60 plasmids have been isolated. These archaeal viruses exhibit an exceptional diversity in morphology, with a wide array of shapes, such as spindles, rods, filaments, spheres, head-tails, bottles, and droplets, and some of these new viruses have been classified into one order, 10 families, and 16 genera. Investigation of model archaeal viruses has yielded important insights into mechanisms underlining various steps in the viral life cycle, including infection, DNA replication and transcription, and virion egression. Many of these mechanisms are unprecedented for any known bacterial or eukaryal viruses. Studies of plasmids isolated from different archaeal hosts have also revealed a striking diversity in gene content and innovation in replication strategies. Highly divergent replication proteins are identified in both viral and plasmid genomes. Genomic studies of archaeal ECEs have revealed a modular sequence structure in which modules of DNA sequence are exchangeable within, as well as among, plasmid families and probably also between viruses and plasmids. In particular, it has been suggested that ECE-host interactions have shaped the coevolution of ECEs and their archaeal hosts. Furthermore, archaeal hosts have developed defense systems, including the innate restriction-modification (R-M) system and the adaptive CRISPR (clustered regularly interspaced short palindromic repeats) system, to restrict invasive plasmids and viruses. Together, these interactions permit a delicate balance between ECEs and their hosts, which is vitally important for maintaining an innovative gene reservoir carried by ECEs. In conclusion, while research on archaeal ECEs has just started to unravel the molecular biology of these genetic entities and their interactions with archaeal hosts, it is expected to accelerate in the next decade. PMID

  5. Extrachromosomal genetic elements in Micrococcus.

    PubMed

    Dib, Julián Rafael; Liebl, Wolfgang; Wagenknecht, Martin; Farías, María Eugenia; Meinhardt, Friedhelm

    2013-01-01

    Micrococci are Gram-positive G + C-rich, nonmotile, nonspore-forming actinomycetous bacteria. Micrococcus comprises ten members, with Micrococcus luteus being the type species. Representatives of the genus play important roles in the biodegradation of xenobiotics, bioremediation processes, production of biotechnologically important enzymes or bioactive compounds, as test strains in biological assays for lysozyme and antibiotics, and as infective agents in immunocompromised humans. The first description of plasmids dates back approximately 28 years, when several extrachromosomal elements ranging in size from 1.5 to 30.2 kb were found in Micrococcus luteus. Up to the present, a number of circular plasmids conferring antibiotic resistance, the ability to degrade aromatic compounds, and osmotolerance are known, as well as cryptic elements with unidentified functions. Here, we review the Micrococcus extrachromosomal traits reported thus far including phages and the only quite recently described large linear extrachromosomal genetic elements, termed linear plasmids, which range in size from 75 kb (pJD12) to 110 kb (pLMA1) and which confer putative advantageous capabilities, such as antibiotic or heavy metal resistances (inferred from sequence analyses and curing experiments). The role of the extrachromosomal elements for the frequently proven ecological and biotechnological versatility of the genus will be addressed as well as their potential for the development and use as genetic tools. PMID:23138713

  6. Extrachromosomal circular DNA is common in yeast

    PubMed Central

    Møller, Henrik D.; Parsons, Lance; Jørgensen, Tue S.; Botstein, David; Regenberg, Birgitte

    2015-01-01

    Examples of extrachromosomal circular DNAs (eccDNAs) are found in many organisms, but their impact on genetic variation at the genome scale has not been investigated. We mapped 1,756 eccDNAs in the Saccharomyces cerevisiae genome using Circle-Seq, a highly sensitive eccDNA purification method. Yeast eccDNAs ranged from an arbitrary lower limit of 1 kb up to 38 kb and covered 23% of the genome, representing thousands of genes. EccDNA arose both from genomic regions with repetitive sequences ≥15 bases long and from regions with short or no repetitive sequences. Some eccDNAs were identified in several yeast populations. These eccDNAs contained ribosomal genes, transposon remnants, and tandemly repeated genes (HXT6/7, ENA1/2/5, and CUP1-1/-2) that were generally enriched on eccDNAs. EccDNAs seemed to be replicated and 80% contained consensus sequences for autonomous replication origins that could explain their maintenance. Our data suggest that eccDNAs are common in S. cerevisiae, where they might contribute substantially to genetic variation and evolution. PMID:26038577

  7. Efficient gene transfer in C.elegans: extrachromosomal maintenance and integration of transforming sequences.

    PubMed Central

    Mello, C C; Kramer, J M; Stinchcomb, D; Ambros, V

    1991-01-01

    We describe a dominant behavioral marker, rol-6(su-1006), and an efficient microinjection procedure which facilitate the recovery of Caenorhabditis elegans transformants. We use these tools to study the mechanism of C.elegans DNA transformation. By injecting mixtures of genetically marked DNA molecules, we show that large extrachromosomal arrays assemble directly from the injected molecules and that homologous recombination drives array assembly. Appropriately placed double-strand breaks stimulated homologous recombination during array formation. Our data indicate that the size of the assembled transgenic structures determines whether or not they will be maintained extrachromosomally or lost. We show that low copy number extrachromosomal transformation can be achieved by adjusting the relative concentration of DNA molecules in the injection mixture. Integration of the injected DNA, though relatively rare, was reproducibly achieved when single-stranded oligonucleotide was co-injected with the double-stranded DNA. Images PMID:1935914

  8. Automatic Detection and Quantification of WBCs and RBCs Using Iterative Structured Circle Detection Algorithm

    PubMed Central

    Alomari, Yazan M.; Zaharatul Azma, Raja

    2014-01-01

    Segmentation and counting of blood cells are considered as an important step that helps to extract features to diagnose some specific diseases like malaria or leukemia. The manual counting of white blood cells (WBCs) and red blood cells (RBCs) in microscopic images is an extremely tedious, time consuming, and inaccurate process. Automatic analysis will allow hematologist experts to perform faster and more accurately. The proposed method uses an iterative structured circle detection algorithm for the segmentation and counting of WBCs and RBCs. The separation of WBCs from RBCs was achieved by thresholding, and specific preprocessing steps were developed for each cell type. Counting was performed for each image using the proposed method based on modified circle detection, which automatically counted the cells. Several modifications were made to the basic (RCD) algorithm to solve the initialization problem, detecting irregular circles (cells), selecting the optimal circle from the candidate circles, determining the number of iterations in a fully dynamic way to enhance algorithm detection, and running time. The validation method used to determine segmentation accuracy was a quantitative analysis that included Precision, Recall, and F-measurement tests. The average accuracy of the proposed method was 95.3% for RBCs and 98.4% for WBCs. PMID:24803955

  9. Ku suppresses formation of telomeric circles and alternative telomere lengthening in Arabidopsis.

    PubMed

    Zellinger, Barbara; Akimcheva, Svetlana; Puizina, Jasna; Schirato, Martina; Riha, Karel

    2007-07-01

    Telomeres in mammals and plants are protected by the terminal t loop structure, the formation of which parallels the first steps of intrachromatid homologous recombination (HR). Under some circumstances, cells can also utilize an HR-based mechanism (alternative lengthening of telomeres [ALT]) as a back-up pathway for telomere maintenance. We have found that the Ku70/80 heterodimer, a central nonhomologous end-joining DNA repair factor, inhibits engagement of ALT in Arabidopsis telomerase-negative cells. To further assess HR activities at telomeres, we have developed a sensitive assay for detecting extrachromosomal telomeric circles (t circles) that may arise from t loop resolution and aberrant HR. We show that Ku70/80 specifically inhibits circle formation at telomeres, but not at centromeric and rDNA repeats. Ku inactivation results in increased formation of t circles that represent approximately 4% of total telomeric DNA. However, telomeres in ku mutants are fully functional, indicating that telomerase efficiently heals ongoing terminal deletions arising from excision of the t circles. PMID:17612498

  10. [Electron microscopic research on the extrachromosomal genetic elements of Escherichia coli].

    PubMed

    Kiseleva, E V; Vorob'eva, N V; Romashchenko, A G; Serdiukova, N A; Khristoliubova, N B

    1986-08-01

    The structural organization of extrachromosomal genetic elements were studied in a subfraction obtained after centrifugation of the lysate of E. coli spheroplasts. With this method of isolation, the tertiary structure of the extrachromosomal genetic elements was preserved. The majority of DNA macromolecules were released in the form of single and connected rosettes. Typical rosettes composed of radial loops of DNA clustered around the central dense core (the diameter is about 60 nm). The mean length of the rosette loops was 1.06 +/- 0.4 micron. Both relaxed folded and supercoiled folded forms of DNA were observed on the preparation. Sometimes the rosettes were connected with large aggregates of DNA (possibly the material of bacterial chromosomes) and had the appearance of thick fibers with numerous lateral loops. Linear, cyclic and various replicative forms of DNA have also been observed. It is assumed that rosettes of the extrachromosomal elements of E. coli reflect one of the levels of organization of prokaryotic genetic material. PMID:3535183

  11. Solving Problems through Circles

    ERIC Educational Resources Information Center

    Grahamslaw, Laura; Henson, Lisa H.

    2015-01-01

    Several problem-solving interventions that utilise a "circle" approach have been applied within the field of educational psychology, for example, Circle Time, Circle of Friends, Sharing Circles, Circle of Adults and Solution Circles. This research explored two interventions, Solution Circles and Circle of Adults, and used thematic…

  12. Analysis of extrachromosomal Ac/Ds transposable elements.

    PubMed Central

    Gorbunova, V; Levy, A A

    2000-01-01

    The mechanism of transposition of the maize Ac/Ds elements is not well understood. The true transposition intermediates are not known and it has not been possible to distinguish between excision models involving 8-bp staggered cuts or 1-bp staggered cuts followed by hairpin formation. In this work, we have analyzed extrachromosomal excision products to gain insight into the excision mechanism. Plasmid rescue was used to demonstrate that Ds excision is associated with the formation of circular molecules. In addition, we present evidence for the formation of linear extrachromosomal species during Ds excision. Sequences found at the termini of circular and linear elements showed a broad range of nucleotide additions or deletions, suggesting that these species are not true intermediates. Additional nucleotides adjacent to the termini in extrachromosomal elements were compared to the sequence of the original donor site. This analysis showed that: (1) the first nucleotide adjacent to the transposon end was significantly more similar to the first nucleotide flanking the element in the donor site than to a random sequence and (2) the second and farther nucleotides did not resemble the donor site. The implications of these findings for excision models are discussed. PMID:10790408

  13. Amplification of a Zygosaccharomyces bailii DNA Segment in Wine Yeast Genomes by Extrachromosomal Circular DNA Formation

    PubMed Central

    Galeote, Virginie; Bigey, Frédéric; Beyne, Emmanuelle; Novo, Maite; Legras, Jean-Luc; Casaregola, Serge; Dequin, Sylvie

    2011-01-01

    We recently described the presence of large chromosomal segments resulting from independent horizontal gene transfer (HGT) events in the genome of Saccharomyces cerevisiae strains, mostly of wine origin. We report here evidence for the amplification of one of these segments, a 17 kb DNA segment from Zygosaccharomyces bailii, in the genome of S. cerevisiae strains. The copy number, organization and location of this region differ considerably between strains, indicating that the insertions are independent and that they are post-HGT events. We identified eight different forms in 28 S. cerevisiae strains, mostly of wine origin, with up to four different copies in a single strain. The organization of these forms and the identification of an autonomously replicating sequence functional in S. cerevisiae, strongly suggest that an extrachromosomal circular DNA (eccDNA) molecule serves as an intermediate in the amplification of the Z. bailii region in yeast genomes. We found little or no sequence similarity at the breakpoint regions, suggesting that the insertions may be mediated by nonhomologous recombination. The diversity between these regions in S. cerevisiae represents roughly one third the divergence among the genomes of wine strains, which confirms the recent origin of this event, posterior to the start of wine strain expansion. This is the first report of a circle-based mechanism for the expansion of a DNA segment, mediated by nonhomologous recombination, in natural yeast populations. PMID:21423766

  14. Alternative model for chromatin organization of the Saccharomyces cerevisiae chromosomal DNA plasmid TRP1 RI circle (YARp1).

    PubMed Central

    Long, C M; Brajkovich, C M; Scott, J F

    1985-01-01

    TRP1 RI circle (now designated YARp1, yeast acentric ring plasmid 1) is a 1,453-base-pair artificial plasmid composed exclusively of Saccharomyces cerevisiae chromosomal DNA. It contains both the TRP1 gene and ARS1 (a DNA sequence that permits extrachromosomal maintenance of recombinant plasmids). This high-copy-number, relatively stable plasmid was shown to be organized into nucleosomes comparable to typical yeast chromatin, containing a possible maximum of nine nucleosomes per circle. Therefore, YARp1 can be used to examine the structure of chromatin of both a chromosomally derived replicator and a functional gene. By mapping regions of micrococcal nuclease cleavage in chromatin versus purified DNA, we located the positions of protected regions on the circle with reference to six unique restriction sites. Measurements made on patterns of early digestion products indicated that a region of approximately 300 base pairs in the vicinity of ARS1 was strongly resistant to micrococcal nuclease. The remainder of the plasmid appeared to be associated with five positioned nucleosomes and two nonnucleosomal, partially protected regions on the bulk of the molecules. After similar extents of digestion, naked DNA did not exhibit an equivalent pattern, although some hypersensitive cleavage sites matched sites found in the chromatin. These results are consistent with the interpretation that the protected domains are aligned with respect to a specific site or sites on the small circular chromatin. Images PMID:3018502

  15. Efficient amplification of self-gelling polypod-like structured DNA by rolling circle amplification and enzymatic digestion

    PubMed Central

    Yata, Tomoya; Takahashi, Yuki; Tan, Mengmeng; Hidaka, Kumi; Sugiyama, Hiroshi; Endo, Masayuki; Takakura, Yoshinobu; Nishikawa, Makiya

    2015-01-01

    The application of DNA as a functional material such as DNA hydrogel has attracted much attention. Despite an increasing interest, the high cost of DNA synthesis is a limiting factor for its utilization. To reduce the cost, we report here a highly efficient amplification technique for polypod-like structured DNA (polypodna) with adhesive ends that spontaneously forms DNA hydrogel. Two types of polypodna with three (tripodna) and four (tetrapodna) pods were selected, and a template oligodeoxynucleotide, containing a tandem sequence of a looped tripodna or tetrapodna, respectively, along with restriction enzyme (TspRI) sites, was designed. The template was circularized using T4 DNA ligase, and amplified by rolling circle amplification (RCA). The RCA product was highly viscous and resistant to restriction digestion. Observation under an electron microscope revealed microflower-like structures. These structures were composed of long DNA and magnesium pyrophosphate, and their treatment with EDTA followed by restriction digestion with TspRI resulted in numerous copies of polypodna with adhesive ends, which formed a DNA hydrogel. Thus, we believe this technique provides a new approach to produce DNA nanostructures, and helps in expanding their practical applications. PMID:26462616

  16. Experimental Analysis of a Paternally Inherited Extrachromosomal Factor

    PubMed Central

    Werren, John H.; van den Assem, Johannes

    1986-01-01

    Virtually all known cases of extrachromosomal inheritance involve cytoplasmic inheritance through the maternal line. Recently, a paternally transmitted factor that causes the production of all-male families has been discovered in a parasitic wasp. The wasp has haplodiploid sex determination: male offspring are haploid and usually develop from unfertilized eggs, whereas females are diploid and usually develop from fertilized eggs. It has been postulated that this paternal sex-ratio factor (psr) is either (1) an infectious agent (a venereal disease) that is transmitted to the female reproductive tract during copulation with an infected male and, subsequently, causes all-male families or (2) a male cytoplasmic factor that is transmitted by sperm to eggs upon egg fertilization and, somehow, causes loss of the paternal set of chromosomes.—Experimental evidence is presented which shows that the factor requires egg fertilization for transmission to the next generation; therefore, it is likely to be a cytoplasmic factor. Significant potential intragenomic conflict results from the presence of this factor and two other sex-ratio distorters in this wasp species. PMID:17246344

  17. Argonaute Proteins Affect siRNA Levels and Accumulation of a Novel Extrachromosomal DNA from the Dictyostelium Retrotransposon DIRS-1*

    PubMed Central

    Boesler, Benjamin; Meier, Doreen; Förstner, Konrad U.; Friedrich, Michael; Hammann, Christian; Sharma, Cynthia M.; Nellen, Wolfgang

    2014-01-01

    The retrotransposon DIRS-1 is the most abundant retroelement in Dictyostelium discoideum and constitutes the pericentromeric heterochromatin of the six chromosomes in D. discoideum. The vast majority of cellular siRNAs is derived from DIRS-1, suggesting that the element is controlled by RNAi-related mechanisms. We investigated the role of two of the five Argonaute proteins of D. discoideum, AgnA and AgnB, in DIRS-1 silencing. Deletion of agnA resulted in the accumulation of DIRS-1 transcripts, the expression of DIRS-1-encoded proteins, and the loss of most DIRS-1-derived secondary siRNAs. Simultaneously, extrachromosomal single-stranded DIRS-1 DNA accumulated in the cytoplasm of agnA− strains. These DNA molecules appear to be products of reverse transcription and thus could represent intermediate structures before transposition. We further show that transitivity of endogenous siRNAs is impaired in agnA− strains. The deletion of agnB alone had no strong effect on DIRS-1 transposon regulation. However, in agnA−/agnB− double mutant strains strongly reduced accumulation of extrachromosomal DNA compared with the single agnA− strains was observed. PMID:25352599

  18. Uncovering novel mobile genetic elements and their dynamics through an extra-chromosomal sequencing approach.

    PubMed

    Deutsch, Douglas R; Utter, Bryan; Fischetti, Vincent A

    2016-01-01

    Staphylococcus aureus is a major clinically important pathogen with well-studied phage contributions to its virulence potential. In this commentary, we describe our method to enrich and sequence stealth extra-chromosomal DNA elements in the bacterial cell, allowing the identification of novel extra-chromosomal prophages in S. aureus clinical strains. Extra-chromosomal sequencing is a useful and broadly applicable tool to study bacterial genomics, giving a temporal glance at the extra-chromosomal compartment of the cell and allowing researchers to uncover lower-copy plasmidial elements (e.g., prophages) as well as gain a greater understanding of mobile genetic elements that shuffle on and off the chromosome. Here, we describe how episomal and plasmidial DNA elements can have profound downstream effects on the host cell and surrounding bacterial population, and discuss specific examples of their importance in Gram-positive bacteria. We also offer potential avenues of future research where extra-chromosomal sequencing may play a key role in our understanding of the complete virulence potential of infectious bacteria. PMID:27581613

  19. Extrachromosomal DNA and cell differentiation in cultured pea roots (Pisum sativum)

    SciTech Connect

    Van't Hof, J.

    1986-01-01

    Histological, cytological and molecular analyses of DNA replication and differentiation and meristematic precursors of vascular parenchyma in cultured pea roots show that the initial steps in the transition from a dividing to a differentiated cell involve retardation of DNA replication in late S phase and production of extrachromosomal molecules by excision from late replicating chromosomal DNA. Portions of the extrachromosomal DNA are displaced by a strand displacement mechanism thereby producing free single-stranded molecules. That extrachromosomal molecules have rDNA reflects the fact that in pea roots replication of the ribosomal genes is maximal during late S phase (unpublished results). It is likely, therefore, that the excised late replicating DNA contains some rDNA sequences. 30 refs., 3 figs.

  20. Recumbent Stone Circles

    NASA Astrophysics Data System (ADS)

    Ruggles, Clive L. N.

    During the 1970s and early 1980s, British archaeoastronomers were striving to bridge the interpretative gulf between the "megalithic observatories" of Alexander Thom and an archaeological mainstream that, generally speaking, was hostile to any mention of astronomy in relation to the megalithic monuments of Neolithic and Early Bronze Age Britain. The Scottish recumbent stone circles (RSCs) came to represent an example where sounder methodology could overcome many of the data selection issues that had beset earlier studies and, with due restraint, produce credible interpretations. Systematic studies of their orientations consistently concluded that the RSCs had a strong lunar connection, and it was widely envisaged that they were the setting for ceremonies associated with the appearance of the moon over the recumbent stone. Other evidence such as the presence of white quartz and the spatial distribution of cupmarks appeared to back up this conclusion. New archaeological investigations since 1999 have challenged and modified these conclusions, confirming in particular that the circles were built to enclose cairns rather than to demarcate open spaces. Yet the restricted pattern of orientations of these structures could only have been achieved by reference to the basic diurnal motions of the skies, and orientation in relation to simple observations of the midsummer moon remains the most likely reading of the alignment evidence taken as a whole. On the other hand, a consideration of the broader context, which includes the nearby Clava cairns, highlights instead the symbolic importance of the sun.

  1. [Willis and his circle].

    PubMed

    van Gijn, Jan; Gijselhart, Joost P

    2012-01-01

    Thomas Willis (1621-1675) grew up in Wiltshire and studied medicine in Oxford, at a time when the city was besieged and then occupied by Parliamentarian troops. He started his career as a country doctor while concurrently taking part in informal gatherings with other scientists (William Petty, Christopher Wren and, later on, Robert Hooke, Richard Lower and Robert Boyle). They performed physical and chemical experiments and carried out a variety of tests on animals. After the restoration of the monarchy in 1660 Willis combined his practice with academic teaching. From then on he focused his studies on the structure and function of the brain, dissecting brains after removal from the skull and fixation in 'spirit of wine'. In his 'Cerebri anatome' of 1664, illustrated by Wren, he drew attention to the arterial circle at the base of the brain, including its physiological advantages. This arterial circle had been incompletely described by others in the past and fully, but only in writing, by Wepfer in 1658. PMID:22436528

  2. Get to Know a Circle

    ERIC Educational Resources Information Center

    Neel-Romine, LeAnn E.; Paul, Sara; Shafer, Kathryn G.

    2012-01-01

    Middle-grades students have a concept image of a circle, but they lack experience in the act of defining. The structure of definitions needs to include conditions that are necessary and sufficient. Most students are able to identify necessary conditions, but they have trouble determining if sufficient conditions are met. How do teachers engage…

  3. Talking Circles Promote Equitable Discourse

    ERIC Educational Resources Information Center

    Hung, Marcus

    2015-01-01

    Teachers facilitate math talk in the classroom, but introducing a structured discussion format called the "talking circle" can influence opportunities for equitable student participation. Drawing on his reflections over the 2013-14 academic year and reviewing his detailed teaching notes and lesson plans, Marcus Hung takes a close look at…

  4. Elimination of extrachromosomally amplified MYC genes from human tumor cells reduces their tumorigenicity.

    PubMed Central

    Von Hoff, D D; McGill, J R; Forseth, B J; Davidson, K K; Bradley, T P; Van Devanter, D R; Wahl, G M

    1992-01-01

    Oncogene amplification has been observed in a broad spectrum of human tumors and has been associated with a poor prognosis for patients with several different types of malignancies. Importantly, at biopsy, the amplified genes localize to acentric extrachromosomal elements such as double-minute chromosomes (DMs) in the vast majority of cases. We show here that treatment of several human tumor cell lines with low concentrations of hydroxyurea accelerates the loss of their extrachromosomally amplified oncogenes. The decreases in MYC copy number in a human tumor cell line correlated with a dramatic reduction in cloning efficiency in soft agar and tumorigenicity in nude mice. No effect on gene copy number or tumorigenicity was observed for a closely related cell line containing the same number of chromosomally amplified MYC genes. One step involved in the accelerated loss of extrachromosomal elements is shown to involve their preferential entrapment of DMs within micronuclei. The data suggest that agents that accelerate the loss of extrachromosomally amplified genes could provide valuable tools for moderating the growth of a large number of human neoplasms. Images PMID:1518843

  5. Polygons and Their Circles

    ERIC Educational Resources Information Center

    Stephenson, Paul

    2009-01-01

    In order to find its circumference, Archimedes famously boxed the circle between two polygons. Ending the first of a series of articles (MT179) with an aside, Francis Lopez-Real reverses the situation to ask: Which polygons can be boxed between two circles? (The official term for such polygons is "bicentric".) The sides of these polygons are…

  6. Literature Circles. ERIC Digest.

    ERIC Educational Resources Information Center

    Lin, Chia-Hui

    The use of literature circles has been discussed in a variety of academic journals, conference papers, and workshops. Teachers at all grade levels use literature circles as a vehicle through which students learn to: think critically about literature; express their thoughts in oral and written forms; and better enjoy their literacy experiences.…

  7. Literature Circles: Getting Started.

    ERIC Educational Resources Information Center

    Fink, Lisa

    Literature Circles are a great way to supplement a reading program in a literature-based classroom. In this lesson plan, students create and answer comprehension questions, discover new vocabulary, and examine elements of literature. The students feel ownership in Literature Circles, because they are responsible for the meeting. Any genre of…

  8. Managing Quality Circles Effectively.

    ERIC Educational Resources Information Center

    Satterwhite, Frank J. Omowale

    Specifically designed for teachers, administrators, and other school decision-makers, this monograph outlines ways quality circles can be used to improve educational planning and decision-making. The first of four sections defines quality circles as a group of workers who identify, analyze, and propose solutions to problems within their scope of…

  9. Sun Circle: An Archeoastronomical Monument

    NASA Astrophysics Data System (ADS)

    Tanz, C.

    2013-04-01

    The Sun Circle is a ceremonial structure in a public park in Tucson, Arizona, designed to track the Sun's movement through the sky over the course of the year. It is also a place where people who use the park—walkers, joggers, bikers, skaters—can pause and sit down and enjoy a little rest. Although it is a modern construction, it draws its inspiration from ancient archeoastronomical structures of the American southwest.

  10. Circle Time in Preschool: An Analysis of Educational Praxis.

    ERIC Educational Resources Information Center

    Reich, Lena Rubinstein

    1994-01-01

    Observations and interviews of five groups of children and staff at different day-care centers found that circle time is both a ritual and a meeting. For staff, circle time allowed for structuring of activities and a sense of accomplishment. For the children, circles were both a positive, affirmatory experience and a restraint, wherein discipline…

  11. T cell receptor gene deletion circles identify recent thymic emigrants in the peripheral T cell pool

    PubMed Central

    Kong, Fan-kun; Chen, Chen-lo H.; Six, Adrien; Hockett, Richard D.; Cooper, Max D.

    1999-01-01

    Progenitor cells undergo T cell receptor (TCR) gene rearrangements during their intrathymic differentiation to become T cells. Rearrangements of the variable (V), diversity (D), and joining (J) segments of the TCR genes result in deletion of the intervening chromosomal DNA and the formation of circular episomes as a byproduct. Detection of these extrachromosomal excision circles in T cells located in the peripheral lymphoid tissues has been viewed as evidence for the existence of extrathymic T cell generation. Because all of the T cells in chickens apparently are generated in the thymus, we have employed this avian model to determine the fate of the V(D)J deletion circles. In normal animals we identified TCR Vγ-Jγ and Vβ-Dβ deletion circles in the blood, spleen, and intestines, as well as in the thymus. Thymectomy resulted in the gradual loss of these DNA deletion circles in all of the peripheral lymphoid tissues. A quantitative PCR analysis of Vγ1-Jγ1 and Vβ1-Dβ deletion circles in splenic γδ and Vβ1+ αβ T cells indicated that their numbers progressively decline after thymectomy with a half-life of approximately 2 weeks. Although TCR deletion circles therefore cannot be regarded as reliable indicators of in situ V(D)J rearrangement, measuring their levels in peripheral T cell samples can provide a valuable index of newly generated T cells entering the T cell pool. PMID:9990059

  12. Epigenetic Repeat-Induced Gene Silencing in the Chromosomal and Extrachromosomal Contexts in Human Cells.

    PubMed

    Mitsuda, Sho-Hei; Shimizu, Noriaki

    2016-01-01

    A plasmid bearing both a replication initiation region and a matrix attachment region is spontaneously amplified in transfected mammalian cells and generates plasmid repeats in the extrachromosomal double minutes (DMs) or the chromosomal homogeneously staining region (HSR). Generally, the repeat sequences are subject to repeat-induced gene silencing, the mechanism of which remains to be elucidated. Previous research showed that gene expression from the same plasmid repeat was higher from repeats located at DMs than at the HSR, which may reflect the extrachromosomal environment of the DMs. In the current study, plasmid repeats in both DMs and HSR were associated with repressive histone modifications (H3K9me3, H3K9me2), and the levels of repressive chromatin markers were higher in HSR than in DMs. Inactive chromatin is known to spread to neighboring regions in chromosome arm. Here, we found that such spreading also occurs in extrachromosomal DMs. Higher levels of active histone modifications (H3K9Ac, H3K4me3, and H3K79me2) were detected at plasmid repeats in DMs than in HSR. The level of DNA CpG methylation was generally low in both DMs and HSR; however, there were some hypermethylated copies within the population of repeated sequences, and the frequency of such copies was higher in DMs than in HSR. Together, these data suggest a "DNA methylation-core and chromatin-spread" model for repeat-induced gene silencing. The unique histone modifications at the extrachromosomal context are discussed with regard to the model. PMID:27525955

  13. Epigenetic Repeat-Induced Gene Silencing in the Chromosomal and Extrachromosomal Contexts in Human Cells

    PubMed Central

    Mitsuda, Sho-hei; Shimizu, Noriaki

    2016-01-01

    A plasmid bearing both a replication initiation region and a matrix attachment region is spontaneously amplified in transfected mammalian cells and generates plasmid repeats in the extrachromosomal double minutes (DMs) or the chromosomal homogeneously staining region (HSR). Generally, the repeat sequences are subject to repeat-induced gene silencing, the mechanism of which remains to be elucidated. Previous research showed that gene expression from the same plasmid repeat was higher from repeats located at DMs than at the HSR, which may reflect the extrachromosomal environment of the DMs. In the current study, plasmid repeats in both DMs and HSR were associated with repressive histone modifications (H3K9me3, H3K9me2), and the levels of repressive chromatin markers were higher in HSR than in DMs. Inactive chromatin is known to spread to neighboring regions in chromosome arm. Here, we found that such spreading also occurs in extrachromosomal DMs. Higher levels of active histone modifications (H3K9Ac, H3K4me3, and H3K79me2) were detected at plasmid repeats in DMs than in HSR. The level of DNA CpG methylation was generally low in both DMs and HSR; however, there were some hypermethylated copies within the population of repeated sequences, and the frequency of such copies was higher in DMs than in HSR. Together, these data suggest a “DNA methylation-core and chromatin-spread” model for repeat-induced gene silencing. The unique histone modifications at the extrachromosomal context are discussed with regard to the model. PMID:27525955

  14. Induction of differentiation in HL60 cells by the reduction of extrachromosomally amplified c-myc.

    PubMed Central

    Eckhardt, S G; Dai, A; Davidson, K K; Forseth, B J; Wahl, G M; Von Hoff, D D

    1994-01-01

    Oncogene amplification in tumor cells results in the overexpression of proteins that confer a growth advantage in vitro and in vivo. Amplified oncogenes can reside intrachromosomally, within homogeneously staining regions (HSRs), or extrachromosomally, within double minute chromosomes (DMs). Since previous studies have shown that low concentrations of hydroxyurea (HU) can eliminate DMs, we studied the use of HU as a gene-targeting agent in tumor cells containing extrachromosomally amplified oncogenes. In a neuroendocrine cell line (COLO 320), we have shown that HU can eliminate amplified copies of c-myc located on DMs, leading to a reduction in tumorigenicity in vitro and in vivo. To determine whether the observed reduction in tumorigenicity was due to differentiation, we next investigated whether HU could induce differentiation in HL60 cells containing extrachromosomally amplified c-myc. We compared the effects of HU, as well as two other known differentiating agents (dimethyl sulfoxide and retinoic acid), on c-myc gene copy number, c-myc expression, and differentiation in HL60 cells containing amplified c-myc genes either on DMs or HSRs. We discovered that HU and dimethyl sulfoxide reduced both c-myc gene copy number and expression and induced differentiation in cells containing c-myc amplified on DMs. These agents failed to have similar effects on HL60 cells with amplified c-myc in HSRs. By contrast, retinoic acid induced differentiation independent of the localization of amplified c-myc. These data illustrate the utility of targeting extrachromosomal DNA to modulate tumor phenotype and reveal that both HU and dimethyl sulfoxide induce differentiation in HL60 cells through DM elimination. Images PMID:8022834

  15. Extrachromosomal DNA of pea (Pisum sativum) root-tip cells replicates by strand displacement

    SciTech Connect

    Krimer, D.B.; Van't Hof, J.

    1983-04-01

    In cultured pea roots there is extrachromosomal DNA associated with cells that differentiate from the G/sub 2/ phase of the cell cycle that is absent from those that differentiate from the G/sub 1/ phase. The authors examined this extrachromosomal DNA by electron microscopy and found that it consisted of three types: (i) double-stranded linear molecules with single-stranded branches (74%), (ii) double-stranded molecules without branches (26%), and (iii) free single-stranded molecules. The double-stranded molecules with or without branches were similar in length, having a modal length of 10-15 ..mu..m. The free single-stranded molecules were shorter and had a mean length of 3.8 ..mu..m. The length of the branches attached to the duplex molecules was only slightly less than that of the free form. The duplex molecules with branches were interpreted as configurations reflecting an ongoing strand-displacement process that results in free single-stranded molecules. Finally, measurements on duplex molecules with multiple branches suggested that the extrachromosomal DNA may exist in the form of tandemly repeated sequences. 8 references, 8 figures.

  16. Beyond the chromosome: the prevalence of unique extra-chromosomal bacteriophages with integrated virulence genes in pathogenic Staphylococcus aureus.

    PubMed

    Utter, Bryan; Deutsch, Douglas R; Schuch, Raymond; Winer, Benjamin Y; Verratti, Kathleen; Bishop-Lilly, Kim; Sozhamannan, Shanmuga; Fischetti, Vincent A

    2014-01-01

    In Staphylococcus aureus, the disease impact of chromosomally integrated prophages on virulence is well described. However, the existence of extra-chromosomal prophages, both plasmidial and episomal, remains obscure. Despite the recent explosion in bacterial and bacteriophage genomic sequencing, studies have failed to specifically focus on extra-chromosomal elements. We selectively enriched and sequenced extra-chromosomal DNA from S. aureus isolates using Roche-454 technology and uncovered evidence for the widespread distribution of multiple extra-chromosomal prophages (ExPΦs) throughout both antibiotic-sensitive and -resistant strains. We completely sequenced one such element comprised of a 43.8 kbp, circular ExPΦ (designated ФBU01) from a vancomycin-intermediate S. aureus (VISA) strain. Assembly and annotation of ФBU01 revealed a number of putative virulence determinants encoded within a bacteriophage immune evasion cluster (IEC). Our identification of several potential ExPΦs and mobile genetic elements (MGEs) also revealed numerous putative virulence factors and antibiotic resistance genes. We describe here a previously unidentified level of genetic diversity of stealth extra-chromosomal elements in S. aureus, including phages with a larger presence outside the chromosome that likely play a prominent role in pathogenesis and strain diversity driven by horizontal gene transfer (HGT). PMID:24963913

  17. Quantization on the circle

    NASA Astrophysics Data System (ADS)

    Merad, M.

    2006-05-01

    We present, via the path-integral approach, the quantum study of a particle without spin constrained to move on a circle and subjected to the action of an external field (V, A). In the first stage, we follow the Faddeev-Senjanovic constraints technique that is essentially based on the Dirac algorithm; and in the second stage, we use the path-integral coherent state relative to the circle, compatible with the topological properties. In the two cases, the free particle and the problem of the magnetic field are shown as an illustrative calculation.

  18. A stem-loop structure, sequence non-specific, at the origin of DNA replication of porcine circovirus is essential for termination but not for initiation of rolling-circle DNA replication

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A stem-loop structure, formed by a pair of inverted repeats during DNA replication, is a conserved feature at the origin of DNA replication among plant and animal viruses, bacteriophages and plasmids that replicate their genomes via the rolling-circle replication (RCR) mechanism. In this work, a hea...

  19. Review: The Closing Circle

    ERIC Educational Resources Information Center

    Environment, 1972

    1972-01-01

    Two views of prominent biologists are presented side-by-side. Focal point is Barry Commoner's book, The Closing Circle, with a subsequent review by Paul Ehrlich. Growth of population, increases in affluence, and increased pollution from products of technology are considered. (BL)

  20. Japanese Quality Control Circles.

    ERIC Educational Resources Information Center

    Nishiyama, Kazuo

    In recent years, United States scholars with an interest in international business and organizational communication have begun to notice the success of Japanese "quality control circles." These are small groups, usually composed of seven to ten workers, who are organized at the production levels within most large Japanese factories. A typical…

  1. Circles Inscribed in Rhombuses

    ERIC Educational Resources Information Center

    Srinivasan, V.K.

    2013-01-01

    In this teaching oriented article, I am introducing the concept of an equilateral rhombus, which is completely characterized. Three main theorems are given with proofs in Section 2. Most of the time, the rhombuses that are discussed are not squares. For a given circle of a specified radius sigma greater than?0, there is exactly one equilateral…

  2. Why Story Circle Matters

    ERIC Educational Resources Information Center

    Lyon, George Ella

    2016-01-01

    If adult attention is screen scrambled, what about kids, whose brains are still developing? In a world where we are over stimulated and hyperlinked-in we are deprived of the kind of time with a person or experience that deepens and sustains us. Here, poet laureate George Ella Lyon writes that the story circle can be such an experience. A school…

  3. Circling "the Scourge"

    ERIC Educational Resources Information Center

    Keller, Bess

    2005-01-01

    In Kenya alone, where the infection rate is estimated to have reached 13 percent of the population, 27,000 teachers will die and more than 2 million children will lose one or both parents to AIDS in the next five years. The Kenyan project uses "study circles," in which teachers learn together about HIV, script new sexual behaviors for themselves,…

  4. QWL Strategies: Quality Circles.

    ERIC Educational Resources Information Center

    Martell, Charles; Tyson, John

    1983-01-01

    Proposes use of quality circles (QCs)--groups of employees who meet to learn and apply techniques for solving problems affecting work or workplace--to involve library employees in decision-making process and improve morale and product/service quality. Basic philosophy, establishment of QC, and QC techniques are noted. Twelve references are…

  5. Collaboration through Study Circles

    ERIC Educational Resources Information Center

    McCoy, Martha L.

    2005-01-01

    Communities are telling inspiring stories about what happens when they use public dialogue and action to involve large numbers of citizens--with the greatest diversity possible--in a search for common ground to resolve tough issues like race, community police relations, and education reform. These efforts, often called "study circles," are…

  6. Literature Circles Go Digital

    ERIC Educational Resources Information Center

    Bromley, Karen; Faughnan, Michelle; Ham, Susan; Miller, Melissa; Armstrong, Traci; Crandall, Cassandra; Garrison, Julia; Marrone, Nicholas

    2014-01-01

    This article describes a literature circle of seven pre-service teacher education students who read "Al Capone Shines My Shoes" (G. Choldenko, 2009). Students used the Internet to complete their roles, shared what they learned as they discussed the book, and then wrote about the digital experience. Four themes emerged from an analysis of…

  7. Inside Larry's Circle

    ERIC Educational Resources Information Center

    Arnold, Alice

    2009-01-01

    Last spring, students from several North Carolina middle schools were invited to participate in the annual Celebrate the Arts festival in Columbus Country. Larry Hewett, a local art teacher, had been selected to instruct the middle-school students. Larry's River Rock Circles project was made as the starting point for the Celebrate the Arts…

  8. Breaking the Sacred Circle.

    ERIC Educational Resources Information Center

    Bill, Willard E.

    Intended as a basis for student discussions on American Indian issues, this article provides background on American Indian and Alaskan Native spiritual values and the white man's disruption of the Sacred Circle of Life. The foundation of the philosophies of North American indigenous peoples was the idea of cyclical reaffirmation and the goal of…

  9. VIEW DOWN BIRCH CIRCLE FROM CORNER OF BIRCH CIRCLE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW DOWN BIRCH CIRCLE FROM CORNER OF BIRCH CIRCLE AND ELM DRIVE. VIEW FACING SOUTHWEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  10. Locating Problems with Quality Circles.

    ERIC Educational Resources Information Center

    White, Donald D.; Bednar, David A.

    1985-01-01

    Five categories of common quality circles problems are identified to help firms anticipate difficulties and avert circle failures. These categories include encountered internal problems, encountered external problems, created internal problems, created external problems, and interface problems. Solutions are suggested. (CT)

  11. Black Pine Circle Project

    ScienceCinema

    Mytko, Christine

    2014-09-15

    A group of seventh graders from Black Pine Circle school in Berkeley had the opportunity to experience the Advanced Light Source (ALS) as "users" via a collaborative field trip and proposal project. The project culminated with a field trip to the ALS for all seventh graders, which included a visit to the ALS data visualization room, a diffraction demonstration, a beamline tour, and informative sessions about x-rays and tomography presented by ALS scientists.

  12. Black Pine Circle Project

    SciTech Connect

    Mytko, Christine

    2014-03-31

    A group of seventh graders from Black Pine Circle school in Berkeley had the opportunity to experience the Advanced Light Source (ALS) as "users" via a collaborative field trip and proposal project. The project culminated with a field trip to the ALS for all seventh graders, which included a visit to the ALS data visualization room, a diffraction demonstration, a beamline tour, and informative sessions about x-rays and tomography presented by ALS scientists.

  13. Visualization and quantitative analysis of extrachromosomal telomere-repeat DNA in individual human cells by Halo-FISH

    PubMed Central

    Komosa, Martin; Root, Heather; Meyn, M. Stephen

    2015-01-01

    Current methods for characterizing extrachromosomal nuclear DNA in mammalian cells do not permit single-cell analysis, are often semi-quantitative and frequently biased toward the detection of circular species. To overcome these limitations, we developed Halo-FISH to visualize and quantitatively analyze extrachromosomal DNA in single cells. We demonstrate Halo-FISH by using it to analyze extrachromosomal telomere-repeat (ECTR) in human cells that use the Alternative Lengthening of Telomeres (ALT) pathway(s) to maintain telomere lengths. We find that GM847 and VA13 ALT cells average ∼80 detectable G/C-strand ECTR DNA molecules/nucleus, while U2OS ALT cells average ∼18 molecules/nucleus. In comparison, human primary and telomerase-positive cells contain <5 ECTR DNA molecules/nucleus. ECTR DNA in ALT cells exhibit striking cell-to-cell variations in number (<20 to >300), range widely in length (<1 to >200 kb) and are composed of primarily G- or C-strand telomere-repeat DNA. Halo-FISH enables, for the first time, the simultaneous analysis of ECTR DNA and chromosomal telomeres in a single cell. We find that ECTR DNA comprises ∼15% of telomere-repeat DNA in GM847 and VA13 cells, but <4% in U2OS cells. In addition to its use in ALT cell analysis, Halo-FISH can facilitate the study of a wide variety of extrachromosomal DNA in mammalian cells. PMID:25662602

  14. Visualization and quantitative analysis of extrachromosomal telomere-repeat DNA in individual human cells by Halo-FISH.

    PubMed

    Komosa, Martin; Root, Heather; Meyn, M Stephen

    2015-02-27

    Current methods for characterizing extrachromosomal nuclear DNA in mammalian cells do not permit single-cell analysis, are often semi-quantitative and frequently biased toward the detection of circular species. To overcome these limitations, we developed Halo-FISH to visualize and quantitatively analyze extrachromosomal DNA in single cells. We demonstrate Halo-FISH by using it to analyze extrachromosomal telomere-repeat (ECTR) in human cells that use the Alternative Lengthening of Telomeres (ALT) pathway(s) to maintain telomere lengths. We find that GM847 and VA13 ALT cells average ∼80 detectable G/C-strand ECTR DNA molecules/nucleus, while U2OS ALT cells average ∼18 molecules/nucleus. In comparison, human primary and telomerase-positive cells contain <5 ECTR DNA molecules/nucleus. ECTR DNA in ALT cells exhibit striking cell-to-cell variations in number (<20 to >300), range widely in length (<1 to >200 kb) and are composed of primarily G- or C-strand telomere-repeat DNA. Halo-FISH enables, for the first time, the simultaneous analysis of ECTR DNA and chromosomal telomeres in a single cell. We find that ECTR DNA comprises ∼15% of telomere-repeat DNA in GM847 and VA13 cells, but <4% in U2OS cells. In addition to its use in ALT cell analysis, Halo-FISH can facilitate the study of a wide variety of extrachromosomal DNA in mammalian cells. PMID:25662602

  15. Introducing healing circles and talking circles into primary care.

    PubMed

    Mehl-Madrona, Lewis; Mainguy, Barbara

    2014-01-01

    We report on the incorporation of a North American aboriginal procedure called "the talking circle" into primary care in areas serving this population. Communication is regulated through the passing of a talking piece (an object of special meaning or symbolism to the circle facilitator, who is usually called the circle keeper). Twelve hundred people participated in talking circles in which 415 attended 4 sessions and completed pre- and postquestionnaires. Outcome measures included baseline and end Measure Your Medical Outcome Profile version 2 forms. Participation in at least 4 talking circles resulted in a statistically significant improvement in reported symptoms and overall quality of life (p < 0.001 and effect sizes ranging from 0.75 to 1.19). The talking circle is a useful tool to use with Native Americans. It may be useful as a means to reduce health care costs by providing other alternative settings to deal with stress-related and other life problems. PMID:24867544

  16. Extrachromosomal recombination substrates recapitulate beyond 12/23 restricted VDJ recombination in nonlymphoid cells.

    PubMed

    Jung, David; Bassing, Craig H; Fugmann, Sebastian D; Cheng, Hwei-Ling; Schatz, David G; Alt, Frederick W

    2003-01-01

    V(D)J recombination occurs efficiently only between gene segments flanked by recombination signals (RSs) containing 12 and 23 base pair spacers (the 12/23 rule). A further limitation "beyond the 12/23 rule" (B12/23) exists at the TCRbeta locus and ensures Dbeta usage. Herein, we show that extrachromosomal V(D)J recombination substrates recapitulate B12/23 restriction in nonlymphoid cells. We further demonstrate that the Vbeta coding flank, the 12-RS heptamer/nonamer, and the 23-RS spacer each can significantly influence B12/23 restriction. Finally, purified core RAG1 and RAG2 proteins (together with HMG2) also reproduce B12/23 restriction in a cell-free system. Our findings indicate that B12/23 restriction of V(D)J recombination is cemented at the level of interactions between the RAG proteins and TCRbeta RS sequences. PMID:12530976

  17. Circle of Ashes

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Circle of Ashes

    This plot tells astronomers that a pulsar, the remnant of a stellar explosion, is surrounded by a disk of its own ashes. The disk, revealed by the two data points at the far right from NASA's Spitzer Space Telescope, is the first ever found around a pulsar. Astronomers believe planets might rise up out of these stellar ashes.

    The data in this plot, or spectrum, were taken by ground-based telescopes and Spitzer. They show that light from around the pulsar can be divided into two categories: direct light from the pulsar, and light from the dusty disk swirling around the pulsar. This excess light was detected by Spitzer's infrared array camera. Dust gives off more infrared light than the pulsar because it's cooler.

    The pulsar, called 4U 0142+61, was once a massive star, until about 100,000 years ago, when it blew up in a supernova explosion and scattered dusty debris into space. Some of that debris was captured into what astronomers refer to as a 'fallback disk,' now circling the leftover stellar core, or pulsar. The disk resembles protoplanetary disks around young stars, out of which planets are thought to be born.

    The data have been corrected to remove the effects of light scattering from dust that lies between Earth and the pulsar.

    The ground-based data is from the Keck I telescope atop Mauna Kea, Hawaii.

  18. Nonselective Persistence of a Rickettsia conorii Extrachromosomal Plasmid during Mammalian Infection.

    PubMed

    Riley, Sean P; Fish, Abigail I; Garza, Daniel A; Banajee, Kaikhushroo H; Harris, Emma K; del Piero, Fabio; Martinez, Juan J

    2016-03-01

    Scientific analysis of the genus Rickettsia is undergoing a rapid period of change with the emergence of viable genetic tools. The development of these tools for the mutagenesis of pathogenic bacteria will permit forward genetic analysis of Rickettsia pathogenesis. Despite these advances, uncertainty still remains regarding the use of plasmids to study these bacteria in in vivo mammalian models of infection, namely, the potential for virulence changes associated with the presence of extrachromosomal DNA and nonselective persistence of plasmids in mammalian models of infection. Here, we describe the transformation of Rickettsia conorii Malish 7 with the plasmid pRam18dRGA[AmTrCh]. Transformed R. conorii stably maintains this plasmid in infected cell cultures, expresses the encoded fluorescent proteins, and exhibits growth kinetics in cell culture similar to those of nontransformed R. conorii. Using a well-established murine model of fatal Mediterranean spotted fever, we demonstrate that R. conorii(pRam18dRGA[AmTrCh]) elicits the same fatal outcomes in animals as its untransformed counterpart and, importantly, maintains the plasmid throughout infection in the absence of selective antibiotic pressure. Interestingly, plasmid-transformed R. conorii was readily observed both in endothelial cells and within circulating leukocytes. Together, our data demonstrate that the presence of an extrachromosomal DNA element in a pathogenic rickettsial species does not affect either in vitro proliferation or in vivo infectivity in models of disease and that plasmids such as pRam18dRGA[AmTrCh] are valuable tools for the further genetic manipulation of pathogenic rickettsiae. PMID:26755154

  19. Oxidative stress and starvation in Dinoroseobacter shibae: the role of extrachromosomal elements

    PubMed Central

    Soora, Maya; Tomasch, Jürgen; Wang, Hui; Michael, Victoria; Petersen, Jörn; Engelen, Bert; Wagner-Döbler, Irene; Cypionka, Heribert

    2015-01-01

    Aerobic anoxygenic phototrophic bacteria (AAP) are abundant in the photic zone of the marine environment. Dinoroseobacter shibae, a representative of the Roseobacter group, converts light into additional energy that enhances its survival especially under starvation. However, light exposure results in the production of cytotoxic reactive oxygen species in AAPs. Here we investigated the response of D. shibae to starvation and oxidative stress, focusing on the role of extrachromosomal elements (ECRs). D. shibae possessing five ECRs (three plasmids and two chromids) was starved for 4 weeks either in the dark or under light/dark cycles and the survival was monitored. Transcriptomics showed that on the chromosome genes with a role in oxidative stress response and photosynthesis were differentially expressed during the light period. Most extrachromosomal genes in contrast showed a general loss of transcriptional activity, especially in dark-starved cells. The observed decrease of gene expression was not due to plasmid loss, as all five ECRs were maintained in the cells. Interestingly, the genes on the 72-kb chromid were the least downregulated, and one region with genes of the oxygen stress response and a light-dependent protochlorophyllide reductase of cyanobacterial origin was strongly activated under the light/dark cycle. A Δ72-kb curing mutant lost the ability to survive under starvation in a light/dark cycle demonstrating the essential role of this chromid for adaptation to starvation and oxidative stress. Our data moreover suggest that the other four ECRs of D. shibae have no vital function under the investigated conditions and therefore were transcriptionally silenced. PMID:25859246

  20. Characterization of Rhizobium grahamii extrachromosomal replicons and their transfer among rhizobia

    PubMed Central

    2014-01-01

    Background Rhizobium grahamii belongs to a new phylogenetic group of rhizobia together with Rhizobium mesoamericanum and other species. R. grahamii has a broad-host-range that includes Leucaena leucocephala and Phaseolus vulgaris, although it is a poor competitor for P. vulgaris nodulation in the presence of Rhizobium etli or Rhizobium phaseoli strains. This work analyzed the genome sequence and transfer properties of R. grahamii plasmids. Results Genome sequence was obtained from R. grahamii CCGE502 type strain isolated from Dalea leporina in Mexico. The CCGE502 genome comprises one chromosome and two extrachromosomal replicons (ERs), pRgrCCGE502a and pRgrCCGE502b. Additionally, a plasmid integrated in the CCGE502 chromosome was found. The genomic comparison of ERs from this group showed that gene content is more variable than average nucleotide identity (ANI). Well conserved nod and nif genes were found in R. grahamii and R. mesoamericanum with some differences. R. phaseoli Ch24-10 genes expressed in bacterial cells in roots were found to be conserved in pRgrCCGE502b. Regarding conjugative transfer we were unable to transfer the R. grahamii CCGE502 symbiotic plasmid and its megaplasmid to other rhizobial hosts but we could transfer the symbiotic plasmid to Agrobacterium tumefaciens with transfer dependent on homoserine lactones. Conclusion Variable degrees of nucleotide identity and gene content conservation were found among the different R. grahamii CCGE502 replicons in comparison to R. mesoamericanum genomes. The extrachromosomal replicons from R. grahamii were more similar to those found in phylogenetically related Rhizobium species. However, limited similarities of R. grahamii CCGE502 symbiotic plasmid and megaplasmid were observed in other more distant Rhizobium species. The set of conserved genes in R. grahamii comprises some of those that are highly expressed in R. phaseoli on plant roots, suggesting that they play an important role in root colonization

  1. Introducing Healing Circles and Talking Circles into Primary Care

    PubMed Central

    Mehl-Madrona, Lewis; Mainguy, Barbara

    2014-01-01

    We report on the incorporation of a North American aboriginal procedure called “the talking circle” into primary care in areas serving this population. Communication is regulated through the passing of a talking piece (an object of special meaning or symbolism to the circle facilitator, who is usually called the circle keeper). Twelve hundred people participated in talking circles in which 415 attended 4 sessions and completed pre- and postquestionnaires. Outcome measures included baseline and end Measure Your Medical Outcome Profile version 2 forms. Participation in at least 4 talking circles resulted in a statistically significant improvement in reported symptoms and overall quality of life (p < 0.001 and effect sizes ranging from 0.75 to 1.19). The talking circle is a useful tool to use with Native Americans. It may be useful as a means to reduce health care costs by providing other alternative settings to deal with stress-related and other life problems. PMID:24867544

  2. Transaction Circles with Digital Texts as a Foundation for Democratic Practices

    ERIC Educational Resources Information Center

    Brown, Sally

    2015-01-01

    Transaction circles weave together elements of guided reading and literature circles in an open conversational structure that supports students as agentive learners. Discourse within these circles utilizing digital informational texts assist in the development of democratic practices even in a time when federal mandates limit curricula and…

  3. Structuring waveguide-grating-based wavelength-division multiplexing/optical code division multiple access network codecs over topology of concentric circles

    NASA Astrophysics Data System (ADS)

    Huang, Jen-Fa; Nieh, Ta-Chun; Chen, Kai-Sheng

    2013-01-01

    The cyclic period and free spectral range of arrayed-waveguide gratings (AWG) in a wavelength-division multiplexing/optical code division multiple access optical code division multiple access network are exploited. The total optical network unit (ONU) of network capacity is partitioned into groups of different wavelength in accordance with the geographical location of subscribers based on the radial distance of the ONU to the optical line terminal. Combining concentric circles round by round for ONU groups enables a fixed round-trip time in the data transmission and a significant increase in system performance. Using AWG router, the proposed topology of concentric circles retains signature orthogonality and minimizes wavelength collisions on the photo-detector. Furthermore, the adoption of extended M-sequence codes corresponding to the AWG codec provides a simpler, more efficient coding procedure and accommodates more users in a single group.

  4. Function of circle of Willis

    PubMed Central

    Vrselja, Zvonimir; Brkic, Hrvoje; Mrdenovic, Stefan; Radic, Radivoje; Curic, Goran

    2014-01-01

    Nearly 400 years ago, Thomas Willis described the arterial ring at the base of the brain (the circle of Willis, CW) and recognized it as a compensatory system in the case of arterial occlusion. This theory is still accepted. We present several arguments that via negativa should discard the compensatory theory. (1) Current theory is anthropocentric; it ignores other species and their analog structures. (2) Arterial pathologies are diseases of old age, appearing after gene propagation. (3) According to the current theory, evolution has foresight. (4) Its commonness among animals indicates that it is probably a convergent evolutionary structure. (5) It was observed that communicating arteries are too small for effective blood flow, and (6) missing or hypoplastic in the majority of the population. We infer that CW, under physiologic conditions, serves as a passive pressure dissipating system; without considerable blood flow, pressure is transferred from the high to low pressure end, the latter being another arterial component of CW. Pressure gradient exists because pulse wave and blood flow arrive into the skull through different cerebral arteries asynchronously, due to arterial tree asymmetry. Therefore, CW and its communicating arteries protect cerebral artery and blood–brain barrier from hemodynamic stress. PMID:24473483

  5. Development of an extrachromosomal cloning vector system for use in Borrelia burgdorferi.

    PubMed

    Sartakova, M; Dobrikova, E; Cabello, F C

    2000-04-25

    Molecular genetic analysis of Borrelia burgdorferi, the cause of Lyme disease, has been hampered by the absence of any means of efficient generation, identification, and complementation of chromosomal and plasmid null gene mutants. The similarity of borrelial G + C content to that of Gram-positive organisms suggested that a wide-host-range plasmid active in Gram-positive bacteria might also be recognized by borrelial DNA replication machinery. One such plasmid, pGK12, is able to propagate in both Gram-positive and Gram-negative bacteria and carries erythromycin and chloramphenicol resistance markers. pGK12 propagated extrachromosomally in B. burgdorferi B31 after electroporation but conferred only erythromycin resistance. pGK12 was used to express enhanced green fluorescent protein in B31 under the control of the flaB promoter. Escherichia coli transformed with pGK12 DNA extracted from B31 expressing only erythromycin resistance developed both erythromycin and chloramphenicol resistance, and plasmid DNA isolated from these transformed E. coli had a restriction pattern similar to the original pGK12. Our data indicate that the replicons of pGK12 can provide the basis to continue developing efficient genetic systems for B. burgdorferi together with the erythromycin resistance and reporter egfp genes. PMID:10781091

  6. Amplicon rearrangements during the extrachromosomal and intrachromosomal amplification process in a glioma

    PubMed Central

    Vogt, Nicolas; Gibaud, Anne; Lemoine, Frédéric; de la Grange, Pierre; Debatisse, Michelle; Malfoy, Bernard

    2014-01-01

    The mechanisms of gene amplification in tumour cells are poorly understood and the relationship between extrachromosomal DNA molecules, named double minutes (dmins), and intrachromosomal homogeneously staining regions (hsr) is not documented at nucleotide resolution. Using fluorescent in situ hybridization and whole genome sequencing, we studied a xenografted human oligodendroglioma where the co-amplification of the EGFR and MYC loci was present in the form of dmins at early passages and of an hsr at later passages. The amplified regions underwent multiple rearrangements and deletions during the formation of the dmins and their transformation into hsr. In both forms of amplification, non-homologous end-joining and microhomology-mediated end-joining rather than replication repair mechanisms prevailed in fusions. Small fragments, some of a few tens of base pairs, were associated in contigs. They came from clusters of breakpoints localized hundreds of kilobases apart in the amplified regions. The characteristics of some pairs of junctions suggest that at least some fragments were not fused randomly but could result from the concomitant repair of neighbouring breakpoints during the interaction of remote DNA sequences. This characterization at nucleotide resolution of the transition between extra- and intrachromosome amplifications highlights a hitherto uncharacterized organization of the amplified regions suggesting the involvement of new mechanisms in their formation. PMID:25378339

  7. Chromosomally and Extrachromosomally Mediated High-Level Gentamicin Resistance in Streptococcus agalactiae.

    PubMed

    Sendi, Parham; Furitsch, Martina; Mauerer, Stefanie; Florindo, Carlos; Kahl, Barbara C; Shabayek, Sarah; Berner, Reinhard; Spellerberg, Barbara

    2016-03-01

    Streptococcus agalactiae (group B Streptococcus [GBS]) is a leading cause of sepsis in neonates. The rate of invasive GBS disease in nonpregnant adults also continues to climb. Aminoglycosides alone have little or no effect on GBS, but synergistic killing with penicillin has been shown in vitro. High-level gentamicin resistance (HLGR) in GBS isolates, however, leads to the loss of a synergistic effect. We therefore performed a multicenter study to determine the frequency of HLGR GBS isolates and to elucidate the molecular mechanisms leading to gentamicin resistance. From eight centers in four countries, 1,128 invasive and colonizing GBS isolates were pooled and investigated for the presence of HLGR. We identified two strains that displayed HLGR (BSU1203 and BSU452), both of which carried the aacA-aphD gene, typically conferring HLGR. However, only one strain (BSU1203) also carried the previously described chromosomal gentamicin resistance transposon designated Tn3706. For the other strain (BSU452), plasmid purification and subsequent DNA sequencing resulted in the detection of plasmid pIP501 carrying a remnant of a Tn3 family transposon. Its ability to confer HLGR was proven by transfer into an Enterococcus faecalis isolate. Conversely, loss of HLGR was documented after curing both GBS BSU452 and the transformed E. faecalis strain from the plasmid. This is the first report showing plasmid-mediated HLGR in GBS. Thus, in our clinical GBS isolates, HLGR is mediated both chromosomally and extrachromosomally. PMID:26729498

  8. Tandem Repeats in Extrachromosomal Ribosomal DNA of Dictyostelium Discoideum, Resulting from Chromosomal Mutations

    PubMed Central

    Cole, R. A.; Williams, K. L.

    1992-01-01

    Extrachromosomal ribosomal DNA in the simple eukaryote Dictyostelium discoideum is readily separated from chromosomal DNA by orthogonal field electrophoresis (OFAGE), forming a prominent band in the 110-kb region of the gel. Here we show that mutations in at least two chromosomal genes give rise to a ladder of rDNA bands increasing in size up to about 300 kb. One of these mutations, the rrcA350 allele, which is recessive to wild type and maps to the centromere-proximal region of linkage group II, has an unstable phenotype; spontaneous revertants, which no longer exhibit the rDNA ladder, have been recovered. Another mutation rrc-351, provisionally mapped to linkage group IV, is dominant to wild type. The rDNA ladder is caused by concatamerization of a 34-kb fragment in the nontranscribed central spacer region of the 88-kb linear rDNA palindrome. Restriction enzyme analysis has revealed that each concatamer is generated by crossovers between two rDNA molecules. PMID:1582557

  9. Introducing Motion in a Circle.

    ERIC Educational Resources Information Center

    Roche, John

    2001-01-01

    Motion in a circle troubled Newton and his contemporaries and troubles students today. Presents a clear presentation of certain aspects, particularly centripetal acceleration and centrifugal force. (Author/MM)

  10. Director Circles of Conic Sections

    ERIC Educational Resources Information Center

    Srinivasan, V. K.

    2002-01-01

    Given a conic section, the locus of a moving point in the plane of the conic section such that the two tangent lines drawn to the conic section from the moving point are all mutually perpendicular is a curve. In the case of an ellipse and hyperbola this curve is a circle referred to as the director circle. In the case of the parabola this curve…

  11. Induction of circles of heterogeneous sizes in carcinogen-treated cells: two-dimensional gel analysis of circular DNA molecules.

    PubMed Central

    Cohen, S; Lavi, S

    1996-01-01

    Extrachromosomal circular DNA molecules are associated with genomic instability, and circles containing inverted repeats were suggested to be the early amplification products. Here we present for the first time the use of neutral-neutral two-dimensional (2D) gel electrophoresis as a technique for the identification, isolation, and characterization of heterogeneous populations of circular molecules. Using this technique, we demonstrated that in N-methyl-N'-nitro-N-nitrosoguanidine-treated simian virus 40-transformed Chinese hamster cells (CO60 cells), the viral sequences are amplified as circular molecules of various sizes. The supercoiled circular fraction was isolated and was shown to contain molecules with inverted repeats. 2D gel analysis of extrachromosomal DNA from CHO cells revealed circular molecules containing highly repetitive DNA which are similar in size to the simian virus 40-amplified molecules. Moreover, enhancement of the amount of circular DNA was observed upon N-methyl-N'-nitro-N-nitrosoguanidine treatment of CHO cells. The implications of these findings regarding the processes of gene amplification and genomic instability and the possible use of the 2D gel technique to study these phenomena are discussed. PMID:8628266

  12. Study Circle Guide: Adult Student Persistence

    ERIC Educational Resources Information Center

    National Center for the Study of Adult Learning and Literacy (NCSALL), 2006

    2006-01-01

    This study circle was created by the National Center for the Study of Adult Learning and Literacy (NCSALL). The study circle is part of NCSALL's efforts to help connect research and practice in the field of adult basic education and adult literacy. The Adult Student Persistence Study Circle is one of a series of study circles that NCSALL has…

  13. Two Circles and Their Common Tangents

    ERIC Educational Resources Information Center

    Srinivasan, V. K.

    2002-01-01

    Given two circles C 1 and C 2 in a plane such that neither one of the two circles is contained in the other, there are either four common tangents when the circles do not intersect at all or the circles have three common tangents when they touch each other externally or only two common tangents when the circles intersect exactly at two points. The…

  14. Regulation and targeting of recombination in extrachromosomal substrates carrying immunoglobulin switch region sequences.

    PubMed Central

    Leung, H; Maizels, N

    1994-01-01

    We have used extrachromosomal substrates carrying immunoglobulin heavy-chain S mu and S gamma 3 switch region sequences to study activation and targeting of recombination by a transcriptional enhancer element. Substrates are transiently introduced into activated primary murine B cells, in which recombination involving S-region sequences deletes a conditionally lethal marker, and recombination is measured by transformation of Escherichia coli in the second step of the assay. Previously we found that as many as 25% of replicated substrates recombined during 40-h transfection of lipopolysaccharide (LPS)-stimulated primary cells and that efficient recombination was dependent on the presence of S-region sequences as well as a transcriptional activator region in the constructs (H. Leung and N. Maizels, Proc. Natl. Acad. Sci. USA 89:4154-4158, 1992). Here we show that recombination of the switch substrates is threefold more efficient in LPS-cultured primary B cells than in the T-cell line EL4; the activities responsible for switch substrate recombination thus appear to be more abundant or more active in cells which can carry out chromosomal switch recombination. We test the role of the transcriptional activator region and show that the immunoglobulin heavy-chain intron enhancer (E mu) alone stimulates recombination as well as E mu combined with a heavy-chain promoter and that mutations that diminish enhancer-dependent transcription 500-fold diminish recombinational activation less than 2-fold. These observations suggest that the enhancer stimulates recombination by a mechanism that does not depend on transcript production or that is insensitive to the level of transcript production over a very broad range. Furthermore, we find that E mu stimulates recombination when located either upstream or downstream of S mu but that the position of the recombinational activator does affect the targeting of recombination junctions, suggesting that the relatively imprecise targeting of

  15. Son-Killer: A Third Extrachromosomal Factor Affecting the Sex Ratio in the Parasitoid Wasp, NASONIA (=MORMONIELLA) VITRIPENNIS

    PubMed Central

    Skinner, Samuel Way

    1985-01-01

    An extrachromosomal factor, termed son-killer (sk), affects the sex ratio in a parasitoid wasp, Nasonia (=Mormoniella ) vitripennis. The factor is maternally transmitted and alters the secondary sex ratio of an infected female through mortality of approximately 80% of the male embryos. No effect on the primary (zygotic) sex ratio is observed. Ninety-five percent of the daughters of an infected female inherit son-killer. The factor can also be transmitted contagiously when the progeny of infected and uninfected females develop simultaneously on a single host. In newly infected strains, the sex ratio effects are equivalent to those in the original. PMID:3988039

  16. Charlotte Circle Outreach. Final Report.

    ERIC Educational Resources Information Center

    Calhoun, Mary Lynne; Rose, Terry L.; Prendergast, Donna

    This final report details the activities of the Charlotte Circle Outreach, a program designed to provide technical assistance and training to early intervention programs offering services to infants and young children with substantial disabilities, ages birth through two years. This mission was accomplished through cooperative planning with…

  17. On a Family of Circles

    ERIC Educational Resources Information Center

    Feeman, Timothy G.

    2011-01-01

    We generalize a standard example from precalculus and calculus texts to give a simple description in polar coordinates of any circle that passes through the origin. We discuss an occurrence of this formula in the context of medical imaging. (Contains 1 figure.)

  18. The Circle Approach to Trigonometry

    ERIC Educational Resources Information Center

    Moore, Kevin c.; LaForest, Kevin R.

    2014-01-01

    How do students think about an angle measure of ninety degrees? How do they think about ratios and values on the unit circle? How might angle measure be used to connect right-triangle trigonometry and circular functions? And why might asking these questions be important when introducing trigonometric functions to students? When teaching…

  19. Making Decisions in Quality Circles.

    ERIC Educational Resources Information Center

    Browne, Mildred

    This monograph provides educational staff with a theoretical basis for decision-making skills for application in quality circles. Roadblocks to good decisions are outlined, as well as the differences between group decision-making and individual decision-making (both have problems). The influence of values and personality characteristics on…

  20. Digital Storytelling: Reinventing Literature Circles

    ERIC Educational Resources Information Center

    Tobin, Maryann Tatum

    2012-01-01

    New literacies in reading research demand the study of comprehension skills using multiple modalities through a more complex, multi-platform view of reading. Taking into account the robust roll of technology in our daily lives, this article presents an update to the traditional literature circle lesson to include digital storytelling and…

  1. On the Circle of Apollonius

    ERIC Educational Resources Information Center

    Ayoub, Ayoub B.

    2006-01-01

    The circle discussed in this paper is named after "The Great Geometer of Antiquity", that is Apollonius of Perga (ca. 262-190 BCE). Among his many contributions to geometry is a book with the title "Plane Loci." This book included, among others, a problem about the locus of a point moving in a plane such that the ratio of its distances from two…

  2. Cervical keratinocytes containing stably replicating extrachromosomal HPV-16 are refractory to transformation by oncogenic H-Ras

    PubMed Central

    Berger, Kristi L.; Barriga, Felicia; Lace, Michael J.; Turek, Lubomir P.; Zamba, Gideon J.; Domann, Frederick E.; Lee, John H.; Klingelhutz, Aloysius J.

    2007-01-01

    Ras expression in human epithelial cells with integrated HPV genomes has been shown to cause tumorigenic transformation. The effects of Ras in cells representing early stage HPV-associated disease (i.e., when HPV is extrachromosomal and the oncogenes are under control of native promoters) have not been examined. Here, we used human cervical keratinocyte cell lines containing stably replicating extrachromosomal HPV-16 and present the novel finding that these cells resist transformation by oncogenic H-Ras. Ras expression consistently diminished anchorageindependent growth (AI), reduced E6 and E7 expression, and caused p53 induction in these cells. Conversely, AI was enhanced or maintained in Ras-transduced cervical cells that were immortalized with a 16E6/E7 retrovirus, and minimal effects on E6 and E7 expression were observed. Ras expression with either episomal HPV-16 or LXSN-E6/E7 was insufficient for tumorigenic growth suggesting that other events are needed for tumorigenic transformation. In conclusion, our results indicate that Ras-mediated transformation depends on the context of HPV oncogene expression and that this is an important point to address when developing HPV tumor models. PMID:16945398

  3. Quality circles: Organizational adaptations, improvements and results

    NASA Technical Reports Server (NTRS)

    Tortorich, R.

    1985-01-01

    The effective application in industry and government of quality circles work was demonstrated. The results achieved in quality and productivity improvements and cost savings are impressive. The circle process should be institutionalized within industry and government. The stages of circle program growth, innovations that help achieve circle process institutionalization, and the result achieved at Martin Marietta's Michoud Division and within the National Aeronautics and Space Administration (NASA) are addressed.

  4. Yarning Circles in the Literacy Classroom

    ERIC Educational Resources Information Center

    Mills, Kathy A.; Sunderland, Naomi; Davis-Warra, John

    2014-01-01

    This article explains how the speaking and listening practice of yarning circles can be used in the literacy classroom. The article opens with an account of a live enactment of yarning circles with elementary students in a mainstream classroom in Australia. It explains the purpose and origin of yarning circles in Indigenous communities, and…

  5. Science Literacy Circles: Big Ideas about Science

    ERIC Educational Resources Information Center

    Devick-Fry, Jane; LeSage, Teresa

    2010-01-01

    Science literacy circles incorporate the organization of both science notebooks and literature circles to help K-8 students internalize big ideas about science. Using science literacy circles gives students opportunities to engage in critical thinking as they inductively develop understanding about science concepts. (Contains 1 table and 7…

  6. Creating Circle of Courage Schools

    ERIC Educational Resources Information Center

    Van Bockern, Steve; McDonald, Tim

    2012-01-01

    Dream what a school would be like in which the purpose is to meet the needs of children and the larger community so that all can lead a good life. Using the Circle of Courage[TM]--a model grounded in values of deep respect for the dignity of all--the authors of this article outline overarching goals and indicators that can turn this dream into…

  7. Resistance of Spiroplasma citri Lines to the Virus SVTS2 Is Associated with Integration of Viral DNA Sequences into Host Chromosomal and Extrachromosomal DNA

    PubMed Central

    Sha, Y.; Melcher, U.; Davis, R. E.; Fletcher, J.

    1995-01-01

    Spiroplasmavirus SVTS2, isolated from Spiroplasma melliferum TS2, produces plaques when inoculated onto lawns of Spiroplasma citri M200H, a derivative of the type strain Maroc R8A2. S. citri strains MR2 and MR3, originally selected as colonies growing within plaques on a lawn of M200H inoculated with SVTS2, were resistant to SVTS2. Genomic DNA fingerprints and electrophoretic protein profiles of M200H, MR2, and MR3 were similar, but three proteins present in M200H were missing or significantly reduced in both resistant lines. None of these three polypeptides reacted with antiserum against S. citri membrane proteins, indicating that they probably are not surface-located virus receptors. Electroporation with SVTS2 DNA produced 1.5 x 10(sup5) transfectants per (mu)g of DNA in M200H but none in MR2 or MR3, suggesting that resistance may result from inhibition of viral replication. The digestion patterns of the extrachromosomal double-stranded (ds) DNA of these lines were similar. Three TaqI fragments of MR2 extrachromosomal DNA that were not present in M200H extrachromosomal DNA hybridized strongly to an SVTS2 probe, and two of these fragments plus an additional one hybridized with the MR3 extrachromosomal DNA, indicating that a fragment of SVTS2 DNA was present in the extrachromosomal ds DNA of MR2 and MR3 but not of M200H. When the restricted genomes of all three lines were probed with SVTS2 DNA, strong hybridization to two EcoRI fragments of chromosomal MR2 and MR3 DNA but not M200H DNA indicated that SVTS2 DNA had integrated into the genomes of MR2 and MR3 but not of M200H. When MR3 extrachromosomal ds DNA containing a 2.1-kb SVTS2 DNA fragment was transfected into M200H, the transformed spiroplasmas were resistant to SVTS2. These results suggest that SVTS2 DNA fragments, possibly integrated into the chromosomal or extrachromosomal DNA of a previously susceptible spiroplasma, may function as viral incompatibility elements, providing resistance to superinfection by

  8. Structures of replication initiation proteins from staphylococcal antibiotic resistance plasmids reveal protein asymmetry and flexibility are necessary for replication.

    PubMed

    Carr, Stephen B; Phillips, Simon E V; Thomas, Christopher D

    2016-03-18

    Antibiotic resistance in pathogenic bacteria is a continual threat to human health, often residing in extrachromosomal plasmid DNA. Plasmids of the pT181 family are widespread and confer various antibiotic resistances to Staphylococcus aureus. They replicate via a rolling circle mechanism that requires a multi-functional, plasmid-encoded replication protein to initiate replication, recruit a helicase to the site of initiation and terminate replication after DNA synthesis is complete. We present the first atomic resolution structures of three such replication proteins that reveal distinct, functionally relevant conformations. The proteins possess a unique active site and have been shown to contain a catalytically essential metal ion that is bound in a manner distinct from that of any other rolling circle replication proteins. These structures are the first examples of the Rep_trans Pfam family providing insights into the replication of numerous antibiotic resistance plasmids from Gram-positive bacteria, Gram-negative phage and the mobilisation of DNA by conjugative transposons. PMID:26792891

  9. Structures of replication initiation proteins from staphylococcal antibiotic resistance plasmids reveal protein asymmetry and flexibility are necessary for replication

    PubMed Central

    Carr, Stephen B.; Phillips, Simon E.V.; Thomas, Christopher D.

    2016-01-01

    Antibiotic resistance in pathogenic bacteria is a continual threat to human health, often residing in extrachromosomal plasmid DNA. Plasmids of the pT181 family are widespread and confer various antibiotic resistances to Staphylococcus aureus. They replicate via a rolling circle mechanism that requires a multi-functional, plasmid-encoded replication protein to initiate replication, recruit a helicase to the site of initiation and terminate replication after DNA synthesis is complete. We present the first atomic resolution structures of three such replication proteins that reveal distinct, functionally relevant conformations. The proteins possess a unique active site and have been shown to contain a catalytically essential metal ion that is bound in a manner distinct from that of any other rolling circle replication proteins. These structures are the first examples of the Rep_trans Pfam family providing insights into the replication of numerous antibiotic resistance plasmids from Gram-positive bacteria, Gram-negative phage and the mobilisation of DNA by conjugative transposons. PMID:26792891

  10. Soma to germline inheritance of extrachromosomal genetic information via a LINE-1 reverse transcriptase-based mechanism.

    PubMed

    Spadafora, Corrado

    2016-08-01

    Mature spermatozoa are permeable to foreign DNA and RNA molecules. Here I propose a model, whereby extrachromosomal genetic information, mostly encoded in the form of RNA in somatic cells, can cross the Weismann barrier and reach epididymal spermatozoa. LINE-1 retrotransposon-derived reverse transcriptase (RT) can play key roles in the process by expanding the RNA-encoded information. Retrotransposon-encoded RT is stored in mature gametes, is highly expressed in early embryos and undifferentiated cells, and becomes downregulated in differentiated cells. In turn, RT plays a role in developmental control, as its inhibition arrests developmental progression of early embryos with globally altered transcriptomic profiles. Thus, sperm cells act as recipients, and transgenerational vectors of somatically derived genetic information which they pass to the next generation with the potential to modify the fate of the developing embryos. PMID:27315018

  11. A Variant of K-Theory and Topological T-Duality for Real Circle Bundles

    NASA Astrophysics Data System (ADS)

    Gomi, Kiyonori

    2015-03-01

    For a space with involutive action, there is a variant of K-theory. Motivated by T-duality in type II orbifold string theory, we establish that a twisted version of the variant enjoys a topological T-duality for Real circle bundles, i.e., circle bundles with real structure.

  12. The Southern Ocean CIRCLE initiative

    NASA Astrophysics Data System (ADS)

    Murphy, E. J.; Ellis-Evans, J. C.

    2003-04-01

    The circumpolar Southern Ocean is the principal ocean connection between the Atlantic, Pacific and Indian Oceans, and exerts a profound influence on world climate through ocean circulation and its major role in the global carbon cycle. It is a major repository of biodiversity and also the only ocean system where significant marine living resources are yet to be fully exploited. However, this key component of the Earth System is still poorly understood, in part due to the logistical problems of a harsh, remote location and the circumpolar nature of the environment. Circumpolar patterns of variability have now been recognized and the current challenge is to understand how, at a circumpolar scale, this variability is generated, its impact on the regional biogeochemical cycles, its interaction with ecosystem processes and the links to global scale processes. Many of these scientific issues can only be addressed by Southern Ocean scale studies, and although a range of national and international research programmes are already targeting particular aspects, the research effort is largely uncoordinated. The European Polar Board is sponsoring a pan-European initiative (Southern Ocean CIRCLE) to coordinate the currently disparate Southern Ocean research effort and this initiative aims to address climate variability, biogeochemical cycling and ecosystem dynamics with particular reference to the links between these aspects in the circumpolar Southern Ocean. This poster outlines the development of the SO CIRCLE initiative, the major areas of science and proposals for implementation. It also outlines how SO CIRCLE will link to other programmes with a Southern Ocean component (e.g. CLIVAR, CliC, GLOBEC, SOLAS). A key aspect of the initiative will be to coordinate European scientific effort in the Southern Ocean with that of the wider international community.

  13. Circle detection using scan lines and histograms

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Zhang, Feng; Du, Zhenhong; Liu, Renyi

    2013-11-01

    Circle detection is significant in image processing and pattern recognition. We present a new algorithm for detecting circles, which is based on the global geometric symmetry of circles. First, the horizontal and vertical midpoint histograms of the edge image are obtained by using scan lines. Then, we apply the peak-finding algorithm to the midpoint histograms to look for the center of the circle. The normalized radius histogram is finally used to verify the existence of the circle and extract its radius. Synthetic images with different levels of pepper noise and real images containing several circles have been taken to test the performance. Experimental results demonstrate that the proposed algorithm has the advantage of computational efficiency as compared with the randomized Hough transform and some other algorithms.

  14. Assessment of the Circle of Willis with Cranial Tomography Angiography

    PubMed Central

    Karatas, Ayse; Coban, Gokmen; Cinar, Celal; Oran, Ismail; Uz, Aysun

    2015-01-01

    Background The circle of Willis is a major collateral pathway important in ischemic conditions. The aim of our study was to assess the structural characteristics of the circle of Willis within the Turkish adult population, along with variations and arteries involved in the measurement of diameters and lengths on cranial computed tomography angiography (CTA). Material/Methods One hundred adult patients who underwent CTA images were evaluated retrospectively. Results Results of the study revealed 82% adult, 17% fetal, and 1% transitional configurations. A complete polygonal structure was observed in 28% of cases. Variations of the circle of Willis were more common in the posterior portion. Hypoplasia was found to be the most common variation and was observed as a maximum in the posterior communicating artery (AComP). Conclusions The patency and size of arteries in the circle of Willis are important in occlusive cerebrovascular diseases and cerebrovascular surgery. Although CTA is an easily accessible non-invasive clinical method for demonstrating the vascular structure, CTA should be evaluated taking into account image resolution quality and difficulties in the identification of small vessels. PMID:26343887

  15. Vortex arrays as emergent collective phenomena for circle swimmers

    NASA Astrophysics Data System (ADS)

    Kaiser, A.; Löwen, H.

    2013-03-01

    Collective properties of many rodlike circle swimmers are explored by computer simulations in two spatial dimensions. In the model considered, the center of mass of a single swimmer moves on a circle with radius R. Therefore, the model provides an interpolation between an interacting self-propelled-rod model for linear swimmers (R→∞) and that of interacting passive rotors (R=0). We map out the state diagram for various swimmer densities and radii R. For increasing density, the dilute state is followed by vortices consisting of single particles (singlet-vortex state), where neighboring particles are perpendicularly oriented, and vortices of swimmer pairs (doublet-vortex state). The vortices exhibit strong structural ordering on an array. At higher densities, a slowed rotor fluid with a significant degree of mutual rotation hindrance occurs. The single-particle vortex structure becomes unstable above a threshold in the circling radius R, while pair vortices are stable only for intermediate radii R. A simple theory is proposed to predict the topology of the state diagram. Our results are verifiable for bacterial and artificial rodlike circle swimmers.

  16. Is that Square Really a Circle?

    ERIC Educational Resources Information Center

    Smith, Christopher E.

    2013-01-01

    While teaching a methods class for preservice secondary school mathematics teachers, Christopher E. Smith found that although all students could draw a reasonably close approximation of a circle, not all could provide an entirely accurate definition of a circle. A discussion with students led him to think about ways of reintroducing students to…

  17. Beyond Quality Circles: Self-Managing Teams.

    ERIC Educational Resources Information Center

    Sims, Henry P., Jr.; Dean, James W., Jr.

    1985-01-01

    This article reviews the quality circle concept, shows why its characteristics appeal to American executives, and examines some of its limitations. It looks at self-managing teams and discusses the reasons that adoptions have been relatively few. It then shows what organizational conditions are necessary for quality circles to evolve into teams.…

  18. The Reading Circle Movement in Texas

    ERIC Educational Resources Information Center

    Spearman, Mindy

    2007-01-01

    In the late-nineteenth and early-twentieth centuries, state-sponsored reading circles provided American teachers with an opportunity for low-cost professional development. Teachers who participated in reading circles read professional literature, discussed the material with colleagues, and, occasionally, completed written assignments based on the…

  19. Drum Circles and the National Standards

    ERIC Educational Resources Information Center

    Fidyk, Steve

    2009-01-01

    The beauty of hand drums is that a child of nearly any age can grab one and get a sound. So how can classroom teachers incorporate this enjoyable activity into something that's actually educational? For young students especially, a drum circle can be liberating. Children can be given various responsibilities--as participants, circle organizers,…

  20. Building Background Knowledge within Literature Circles

    ERIC Educational Resources Information Center

    Barone, Diane; Barone, Rebecca

    2012-01-01

    The authors examined the strength of literature circles in developing background knowledge--an acknowledged sticking point in the development of understanding for middle graders--with a special focus on the literature circle role of "investigator," where it is student initiative and not teacher direction that guides comprehension. Observing…

  1. Developing Soft Skills Using "Literature Circles"

    ERIC Educational Resources Information Center

    Azmi, Mohd Nazri Bin Latiff

    2013-01-01

    This study investigates the impact of the implementation of "Literature Circles" in an Active Learning classroom in relations to developing soft skills among university students. The use of Literature Circles is a well-known strategy in teaching the students to be more creative, independent, and think out of the box. A group of…

  2. Unit Circles and Inverse Trigonometric Functions

    ERIC Educational Resources Information Center

    Barrera, Azael

    2014-01-01

    Historical accounts of trigonometry refer to the works of many Indian and Arab astronomers on the origin of the trigonometric functions as we know them now, in particular Abu al-Wafa (ca. 980 CE), who determined and named all known trigonometric functions from segments constructed on a regular circle and later on a unit circle (Moussa 2011;…

  3. Small RNA-based feedforward loop with AND-gate logic regulates extrachromosomal DNA transfer in Salmonella

    PubMed Central

    Papenfort, Kai; Espinosa, Elena; Casadesús, Josep; Vogel, Jörg

    2015-01-01

    Horizontal gene transfer via plasmid conjugation is a major driving force in microbial evolution but constitutes a complex process that requires synchronization with the physiological state of the host bacteria. Although several host transcription factors are known to regulate plasmid-borne transfer genes, RNA-based regulatory circuits for host–plasmid communication remain unknown. We describe a posttranscriptional mechanism whereby the Hfq-dependent small RNA, RprA, inhibits transfer of pSLT, the virulence plasmid of Salmonella enterica. RprA employs two separate seed-pairing domains to activate the mRNAs of both the sigma-factor σS and the RicI protein, a previously uncharacterized membrane protein here shown to inhibit conjugation. Transcription of ricI requires σS and, together, RprA and σS orchestrate a coherent feedforward loop with AND-gate logic to tightly control the activation of RicI synthesis. RicI interacts with the conjugation apparatus protein TraV and limits plasmid transfer under membrane-damaging conditions. To our knowledge, this study reports the first small RNA-controlled feedforward loop relying on posttranscriptional activation of two independent targets and an unexpected role of the conserved RprA small RNA in controlling extrachromosomal DNA transfer. PMID:26307765

  4. Extrachromosomal homologous DNA recombination in plant cells is fast and is not affected by CpG methylation.

    PubMed Central

    Puchta, H; Kocher, S; Hohn, B

    1992-01-01

    Using a sensitive transient assay, we investigated extrachromosomal homologous DNA recombination (ECR) in plant cells. As the plant genome is highly C methylated, we addressed the question of whether CpG methylation has an influence on DNA recombination efficiencies. Whereas the expression level of the fully CpG-methylated DNA molecules was reduced drastically, we found no significant changes in ECR efficiencies between two partly CpG-methylated plasmids or between one fully CpG-methylated and one nonmethylated plasmid. Using a modified polymerase chain reaction analysis, we were able to detect recombination between two fully CpG-methylated plasmids. Furthermore, we characterized the kinetics of the ECR reaction. Cotransfection of plasmids carrying truncated copies of the beta-glucuronidase (GUS) gene resulted in enzyme activity with a delay of only half an hour compared with that of the plasmid carrying the functional marker gene. This indicates that the ECR reaction itself requires no more than 30 min. By polymerase chain reaction, we were able to detect the recombined GUS gene as early as 2 h after transfection. This result and the time course of the transient GUS activity indicate that ECR occurs mainly early after transfection. The biological significance of this finding is discussed, and properties of ECR and intrachromosomal recombination are compared. Images PMID:1630452

  5. Biomechanical analysis of circles on pommel horse.

    PubMed

    Fujihara, Toshiyuki; Fuchimoto, Takafumi; Gervais, Pierre

    2009-03-01

    The aim of this study was to analyse the principal mechanics of circles. Seventeen university male gymnasts performed circles on an instrumented pommel horse model that enabled the pommel reaction forces to be recorded at 1000 Hz with two force plates. The circles were also videotaped using two digital video cameras operating at 60 frames per second. During circles, the vertical component of the reaction forces peaked in the double-hand support phases. Changes in the velocity of the centre of mass corresponded to the change in the tangential components of horizontal reaction forces. The velocity of the centre of mass had its peaks in the single-hand support phases and its local minimums in the double-hand support phases. The velocity of the ankles and that of the centre of mass of the head and trunk were minimal in the single-hand support phases and were maximal in the double-hand support phases. These results suggest that the circles were composed of vertical movements and two kinds of rotations: rotation of the centre of mass and rotation of the body itself about the centre of mass. These two kinds of rotations, which influence the legs' rotational velocity, are phase dependent. To further our understanding of circles, research on circles in different orientations on the pommel horse will be beneficial. PMID:19391492

  6. Effects of substrate structure on the kinetics of circle opening reactions of the self-splicing intervening sequence from Tetrahymena thermophila: evidence for substrate and Mg2+ binding interactions.

    PubMed Central

    Sugimoto, N; Tomka, M; Kierzek, R; Bevilacqua, P C; Turner, D H

    1989-01-01

    The self-splicing intervening sequence from the precursor rRNA of Tetrahymena thermophila cyclizes to form a covalently closed circle. This circle can be reopened by reaction with oligonucleotides or water. The kinetics of circle opening as a function of substrate and Mg2+ concentrations have been measured for dCrU, rCdU, dCdT, and H2O addition. Comparisons with previous results for rCrU suggest: (1) the 2' OH of the 5' sugar of a dinucleoside phosphate is involved in substrate binding, and (2) the 2' OH of the 3' sugar of a dimer substrate is involved in Mg2+ binding. Evidently, the binding site for a required Mg2+ ion is dependent on both the ribozyme and the dimer substrate. The apparent activation energy and entropy for circle opening by hydrolysis are 31 kcal/mol and 50 eu, respectively. The large, positive activation entropy suggests a partial unfolding of the ribozyme is required for reaction. Images PMID:2643083

  7. The experience of meaning in circle dance

    PubMed Central

    Borges da Costa, Ana L.; Cox, Diane L.

    2016-01-01

    ABSTRACT Circle dance, which derives from the tradition of folk dances, is practised worldwide. This article explores the meanings participants attribute to it. In-depth interviews with 39 participants, teachers and coordinators of teacher training programmes from the circle dance network in the United Kingdom were undertaken. Applying a constructivist grounded theory approach, major categories, representing respectively the experiences of circle dance participants, teachers and coordinators, were developed. This article specifically focuses on the first major category, termed “I can't imagine life without it”, which relates to the experience of 22 dancers. From an occupational perspective, the study reveals how participants realise a sense of meaning and satisfaction through engagement in circle dance and the potential contribution of this occupation to well-being. PMID:27366111

  8. Quality Circles and Health Promotion Planning.

    ERIC Educational Resources Information Center

    Galli, Nicholas; Corry, James M.

    1986-01-01

    This article explores the process of health education program planning, presents the model of quality circles, and examines the variables upon which decisions for or against specific programs are made within an institution. (MT)

  9. Teachers' Pets II--Circling Carts

    ERIC Educational Resources Information Center

    Gardner, Robert

    1975-01-01

    Describes a demonstration which illustrates that a body moving with constant speed can be accelerating. The students ride in a circle on a cart made with plywood and roller skates and equipped with bubble accelerometers. (MLH)

  10. [Health education based on culture circles].

    PubMed

    Monteiro, Estela Maria Leite Meirelles; Vieira, Neiva Francenely Cunha

    2010-01-01

    This study aims at systematizing with the participants of Culture Circles a proposal of reconstruction of actions of health education that show the necessary competences to the nurses of Family Health Program for a practice in education on critical and reflexive health. It is constituted of a research action, where the researcher based in "Paulo Freire Method" is encouraging debates in eight Culture Circles having the participation of ten nurses. The Circles give them the training of a political conscience , essential to the process of " empowerment " of the health professional in practicing his socio-politics competence. The proposal of achieving the Culture Circles establish a link of complicity between health professionals and communitarian groups with the actions of health promotion. PMID:20658073

  11. Dark circles: etiology and management options.

    PubMed

    Friedmann, Daniel P; Goldman, Mitchel P

    2015-01-01

    Given their multifactorial nature and the fact that individual patients may have more than a single underlying cause, cosmetic practitioners should be well versed in a number of potential treatment options encompassing all facets of under-eye dark circles. New therapeutic options are also forthcoming. Longer-lasting HA fillers, wavelength tunable laser devices, and topicals speeding up healing and enhancing results after fractionated laser therapy will all serve to make the future of dark circle treatment unabatedly bright. PMID:25440739

  12. Sets that Contain Their Circle Centers

    ERIC Educational Resources Information Center

    Martin, Greg

    2008-01-01

    Say that a subset S of the plane is a "circle-center set" if S is not a subset of a line, and whenever we choose three non-collinear points from S, the center of the circle through those three points is also an element of S. A problem appearing on the Macalester College Problem of the Week website stated that a finite set of points in the plane,…

  13. Rapid Evolution of Recombinant Saccharomyces cerevisiae for Xylose Fermentation through Formation of Extra-chromosomal Circular DNA

    PubMed Central

    Demeke, Mekonnen M.; Foulquié-Moreno, María R.; Dumortier, Françoise; Thevelein, Johan M.

    2015-01-01

    Circular DNA elements are involved in genome plasticity, particularly of tandem repeats. However, amplifications of DNA segments in Saccharomyces cerevisiae reported so far involve pre-existing repetitive sequences such as ribosomal DNA, Ty elements and Long Terminal Repeats (LTRs). Here, we report the generation of an eccDNA, (extrachromosomal circular DNA element) in a region without any repetitive sequences during an adaptive evolution experiment. We performed whole genome sequence comparison between an efficient D-xylose fermenting yeast strain developed by metabolic and evolutionary engineering, and its parent industrial strain. We found that the heterologous gene XylA that had been inserted close to an ARS sequence in the parent strain has been amplified about 9 fold in both alleles of the chromosomal locus of the evolved strain compared to its parent. Analysis of the amplification process during the adaptive evolution revealed formation of a XylA-carrying eccDNA, pXI2-6, followed by chromosomal integration in tandem arrays over the course of the evolutionary adaptation. Formation of the eccDNA occurred in the absence of any repetitive DNA elements, probably using a micro-homology sequence of 8 nucleotides flanking the amplified sequence. We isolated the pXI2-6 eccDNA from an intermediate strain of the evolutionary adaptation process, sequenced it completely and showed that it confers high xylose fermentation capacity when it is transferred to a new strain. In this way, we have provided clear evidence that gene amplification can occur through generation of eccDNA without the presence of flanking repetitive sequences and can serve as a rapid means of adaptation to selection pressure. PMID:25738959

  14. Analysis of the VPE sequences in the Caenorhabditis elegans vit-2 promoter with extrachromosomal tandem array-containing transgenic strains.

    PubMed Central

    MacMorris, M; Spieth, J; Madej, C; Lea, K; Blumenthal, T

    1994-01-01

    The Caenorhabditis elegans vit genes, encoding vitellogenins, are abundantly expressed in the adult hermaphrodite intestine. Two repeated elements, vit promoter element 1 (VPE1 [TGTCAAT]) and VPE2 (CTGATAA), have been identified in the 5' flanking DNA of each of the vit genes of C. elegans and Caenorhabditis briggsae. These elements have previously been shown to be needed for correctly regulated expression of a vit-2/vit-6 fusion gene in low-copy-number, integrated transgenes. Here we extend the analysis of the function of VPE1 and VPE2 by using transgenic lines carrying large, extrachromosomal arrays of the test genes. The results validate the use of such arrays for transgenic analysis of gene regulation in C. elegans, by confirming previous findings showing that the VPE1 at -45 and both VPE2s are sites of activation. Additional experiments now indicate that when the -45 VPE1 is inverted or replaced by a VPE2, nearly total loss of promoter function results, suggesting that the highly conserved -45 VPE1 plays a unique role in vit-2 promoter function. In contrast, single mutations eliminating the three upstream VPE1s are without effect. However, in combination in double and triple mutants, these upstream VPE1 mutations cause drastic reductions in expression levels. The -150 VPE2 can be replaced by a XhoI site (CTCGAG), and the -90 VPE2 can be eliminated, as long as the overlapping VPE1 is left intact, but when these two replacements are combined, activity is lost. Thus, the promoter must have at least one VPE2 and it must have at least two VPE1s, one at -45 and one additional upstream element. Images PMID:8264616

  15. Characterization of the extrachromosomal function (ECF) sigma factors of Arcobacter butzleri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Campylobacter jejuni is the most commonly reported cause of bacterial foodborne illness in North America. C. jejuni decorates its surface polysaccharides with a variety of variable phosphorylated structures, including O-methyl phosphoramidate (MeOPN) modifications on the capsular polysaccharide. Alt...

  16. Physiological and lifestyle factors contributing to risk and severity of peri-orbital dark circles in the Brazilian population*

    PubMed Central

    Matsui, Mary S; Schalka, Sérgio; Vanderover, Garrett; Fthenakis, Christina G.; Christopher, J; Bombarda, Patricia Camarano Pinto; Bueno, Juliana Regina; Viscomi, Bianca Lenci Inácio; Bombarda Júnior, Mário Sérgio

    2015-01-01

    BACKGROUND Peri-orbital dark circles are a cosmetic concern worldwide, and have been attributed to hyperpigmentation from allergy or atopic dermatitis, blood stasis, structural shadowing effects, and a thin epidermis/dermis under the eye. It is of interest to better understand lifestyle and demographic risk factors and the relative impact of melanin, blood and epidermal/dermal factors on the severity of Peri-orbital dark circles. OBJECTIVE To compare by non-invasive imaging the impact of biological factors to a visual grading scale for Peri-orbital dark circles, and test the correlation of various demographic factors with Peri-orbital dark circles. METHODS Subjects completed a lifestyle and health survey, and Peri-orbital dark circles severity was evaluated using standardized photographs. Hyperspectral image analysis was used to assess the contributions of melanin, blood volume, degree of blood oxygen saturation, and dermal scattering. RESULTS Family history was the most significant risk factor for Peri-orbital dark circles. The average age of onset was 24 years, and earlier onset correlated with higher severity scores. Asthma was significantly associated with Peri-orbital dark circles scores, but self-reported allergy was not. In this study, sleep was not correlated with Peri-orbital dark circles scores. Hyperspectral imaging indicated that melanin was the dominant correlate for Peri-orbital dark circles severity, while oxygen saturation was secondary. The difference between under-eye and cheek measurements for ∆L*and ∆E* were the most significant instrumental parameters correlated with visual assessment of Peri-orbital dark circles severity. CONCLUSION Although typically associated with lack of sleep, risk of Peri-orbital dark circles is primarily hereditary. The main factors contributing to the appearance of Peri-orbital dark circles are melanin and (deoxygenated) blood. PMID:26375218

  17. Experiments Testing the Causes of Namibian Fairy Circles

    PubMed Central

    Tschinkel, Walter R.

    2015-01-01

    The grasslands on the sandy soils of the eastern edge of the Namib Desert of Namibia are strikingly punctuated by millions of mostly regularly-spaced circular bare spots 2 to 10 m or more in diameter, generally with a margin of taller grasses. The causes of these so called fairy circles are unknown, but several hypotheses have been advanced. In October 2009, we set up experiments that specifically tested four hypothesized causes, and monitored these 5 times between 2009 and 2015. Grass exclusion in circles due to seepage of subterranean vapors or gases was tested by burying an impermeable barrier beneath fairy circles, but seedling density and growth did not differ from barrier-less controls. Plant germination and growth inhibition by allelochemicals or nutrient deficiencies in fairy circle soils were tested by transferring fairy circle soil to artificially cleared circles in the grassy matrix, and matrix soil to fairy circles (along with circle to circle and matrix to matrix controls). None of the transfers changed the seedling density and growth from the control reference conditions. Limitation of plant growth due to micronutrient depletion within fairy circles was tested by supplementing circles with a micronutrient mixture, but did not result in differences in plant seedling density and growth. Short-range vegetation competitive feedbacks were tested by creating artificially-cleared circles of 2 or 4 m diameter located 2 or 6 m from a natural fairy circle. The natural circles remained bare and the artificial circles revegetated. These four experiments provided evidence that fairy circles were not caused by subterranean vapors, that fairy circle soil per se did not inhibit plant growth, and that the circles were not caused by micronutrient deficiency. There was also no evidence that vegetative feedbacks affected fairy circles on a 2 to 10 m scale. Landscape-scale vegetative self-organization is discussed as a more likely cause of fairy circles. PMID:26510015

  18. Expanding-Circle Students Learning "Standard English" in the Outer-Circle Asia

    ERIC Educational Resources Information Center

    Kobayashi, Yoko

    2011-01-01

    Drawing upon Kachru's concentric circles of English, the present study explores whether middle-class Japanese students who chose to study English solo at private language schools in Singapore diverge from many others who (wish to) study inner-circle English. The study is stimulated by the repeated interdisciplinary findings that, in spite of the…

  19. Gradual regime shifts in fairy circles

    PubMed Central

    Zelnik, Yuval R.; Meron, Ehud; Bel, Golan

    2015-01-01

    Large responses of ecosystems to small changes in the conditions—regime shifts—are of great interest and importance. In spatially extended ecosystems, these shifts may be local or global. Using empirical data and mathematical modeling, we investigated the dynamics of the Namibian fairy circle ecosystem as a case study of regime shifts in a pattern-forming ecosystem. Our results provide new support, based on the dynamics of the ecosystem, for the view of fairy circles as a self-organization phenomenon driven by water–vegetation interactions. The study further suggests that fairy circle birth and death processes correspond to spatially confined transitions between alternative stable states. Cascades of such transitions, possible in various pattern-forming systems, result in gradual rather than abrupt regime shifts. PMID:26362787

  20. Generic Rigidity for Circle Diffeomorphisms with Breaks

    NASA Astrophysics Data System (ADS)

    Kocić, Saša

    2016-05-01

    We prove that C^r -smooth (r > 2 ) circle diffeomorphisms with a break, i.e., circle diffeomorphisms with a single singular point where the derivative has a jump discontinuity, are generically, i.e., for almost all irrational rotation numbers, not C^1+ɛ -rigid, for any ɛ > 0 . This result complements our recent proof, joint with Khanin (Geom Funct Anal 24:2002-2028, 2014), that such maps are generically C^1 -rigid. It stands in remarkable contrast to the result of Yoccoz (Ann Sci Ec Norm Sup 17:333-361, 1984) that C^r -smooth circle diffeomorphisms are generically C^r-1-κ -rigid, for any κ > 0.

  1. Gradual regime shifts in fairy circles.

    PubMed

    Zelnik, Yuval R; Meron, Ehud; Bel, Golan

    2015-10-01

    Large responses of ecosystems to small changes in the conditions--regime shifts--are of great interest and importance. In spatially extended ecosystems, these shifts may be local or global. Using empirical data and mathematical modeling, we investigated the dynamics of the Namibian fairy circle ecosystem as a case study of regime shifts in a pattern-forming ecosystem. Our results provide new support, based on the dynamics of the ecosystem, for the view of fairy circles as a self-organization phenomenon driven by water-vegetation interactions. The study further suggests that fairy circle birth and death processes correspond to spatially confined transitions between alternative stable states. Cascades of such transitions, possible in various pattern-forming systems, result in gradual rather than abrupt regime shifts. PMID:26362787

  2. Generic Rigidity for Circle Diffeomorphisms with Breaks

    NASA Astrophysics Data System (ADS)

    Kocić, Saša

    2016-06-01

    We prove that {C^r}-smooth ({r > 2}) circle diffeomorphisms with a break, i.e., circle diffeomorphisms with a single singular point where the derivative has a jump discontinuity, are generically, i.e., for almost all irrational rotation numbers, not {C^{1+\\varepsilon}}-rigid, for any {\\varepsilon > 0}. This result complements our recent proof, joint with Khanin (Geom Funct Anal 24:2002-2028, 2014), that such maps are generically {C^1}-rigid. It stands in remarkable contrast to the result of Yoccoz (Ann Sci Ec Norm Sup 17:333-361, 1984) that {C^r}-smooth circle diffeomorphisms are generically {C^{r-1-κ}}-rigid, for any {κ > 0}.

  3. Double devil's staircase in circle maps

    NASA Astrophysics Data System (ADS)

    Jazaeri, Amin; Satija, Indubala I.

    1992-07-01

    Motivated by the existence of a fractal phase boundary for the occurrence of Kolmogorov-Arnold-Moser tori in two-parameter area-preserving maps, we study the two-parameter circle map with two inflection points. The critical surface of the mode-locked windows is found to obey additive rules for the bistability regimes caused by cusp catastrophe. This results in the double devil's staircase for the mode-locked windows and a fractal curve for a critical set of parameter values for the breakup of the invariant circles.

  4. Reflection positivity for the circle group

    NASA Astrophysics Data System (ADS)

    Neeb, K.-H.; Ólafsson, G.

    2015-04-01

    In this note we characterize those unitary one-parameter groups (Utc)t∈R which admit euclidean realizations in the sense that they are obtained by the analytic continuation process corresponding to reflection positivity from a unitary representation U of the circle group. These are precisely the ones for which there exists an anti-unitary involution J commuting with Uc. This provides an interesting link with the modular data arising in Tomita-Takesaki theory. Introducing the concept of a positive definite function with values in the space of sesquilinear forms, we further establish a link between KMS states and reflection positivity on the circle.

  5. Literature Circles Go to College

    ERIC Educational Resources Information Center

    Levy, Ronna J.

    2011-01-01

    In basic writing classrooms and scholarship, reading too often remains invisible; neither research nor established practice provides tangible activities to support reading and connect it to writing. This article documents a search for structured, scaffolded, low-stakes reading activities, a search that moves off the college campus and into the…

  6. Circles and the Lines That Intersect Them

    ERIC Educational Resources Information Center

    Clay, Ellen L.; Rhee, Katherine L.

    2014-01-01

    In this article, Clay and Rhee use the mathematics topic of circles and the lines that intersect them to introduce the idea of looking at the single mathematical idea of relationships--in this case, between angles and arcs--across a group of problems. They introduce the mathematics that underlies these relationships, beginning with the questions…

  7. Community Social Work and the Learning Circle

    ERIC Educational Resources Information Center

    Lavan, Ann

    2008-01-01

    Outlines an approach for introducing students to Community Social Work by use of clear, engaging stated objectives. Approach is called the Learning Circle and was devised as a tool to enhance student participation and to stimulate networking, dialogue and conversation about social work commitment to community intervention and community-based…

  8. Conversations among Writers in Authors Circles.

    ERIC Educational Resources Information Center

    Villaume, Susan Kidd; Brabham, Edna Greene

    2001-01-01

    Searches for examples of Authors Circles by talking with classroom teachers, surveying recent editions of this and other journals, and scanning library shelves for books on workshops and methods that incorporate student discussion with the teaching of writing. Discovers that descriptions of teacher-student conferences dominate explanations,…

  9. Literature Circles as Support for Language Development

    ERIC Educational Resources Information Center

    Elhess, Mohamed; Egbert, Joy

    2015-01-01

    There are many instructional approaches for helping English language learners improve both reading comprehension and overall language proficiency. One such approach, the literature circle--which is somewhat like a student book club in the classroom--has drawn a great deal of attention in recent years (Schlick Noe and Johnson 1999). Many teachers…

  10. Syllable Circles for Pronunciation Learning and Teaching

    ERIC Educational Resources Information Center

    Whipple, John; Cullen, Charlie; Gardiner, Keith; Savage, Tim

    2015-01-01

    Syllable Circles are interactive visualizations representing prominence as a feature in short phrases or multi-syllable words. They were designed for computer-aided pronunciation teaching. This study explores whether and how interactive visualizations can affect language learners' awareness of prominence, or stress, in English pronunciation. The…

  11. Promoting Staff Support in Schools: Solution Circles

    ERIC Educational Resources Information Center

    Brown, Emma; Henderson, Linda

    2012-01-01

    The Solution Circle (SC) approach is a flexible tool which encourages participants to maintain a positive, creative approach to problem-solving. This project focussed on the introduction of this approach to staff in a primary and a secondary school. The rationale was to implement a problem-solving/discussion tool that would allow staff to utilise…

  12. Adult Multiple Intelligences. NCSALL Study Circle Guide

    ERIC Educational Resources Information Center

    Parrella, A.; Hofer, J.; Bubp, S.; Finn-Miller, S.; Graves, N.; Meador, P.

    2004-01-01

    This Study Circle guide was created by the National Center for the Study of Adult Learning and Literacy (NCSALL) as part of the Practitioner Dissemination and Research Network (PDRN). The guide is part of NCSALL's effort to help connect research and practice in the field of adult basic education and adult literacy. The purpose of the study circle…

  13. Raccoon Circles: A Handbook for Facilitators.

    ERIC Educational Resources Information Center

    Cain, Jim

    This handbook presents a collection of over 35 experiential and adventure-based activities using only a single item of equipment--a 15-foot long section of 1-inch tubular climbing webbing, called a raccoon circle. Some of the activities are quiet, some are loud, and they range from low to high challenge levels. Different-sized groups can be…

  14. VIEW OF NORTHWEST BEND IN BIRCH CIRCLE. VIEW FACING WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF NORTHWEST BEND IN BIRCH CIRCLE. VIEW FACING WEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  15. VIEW OF BIRCH CIRCLE, FROM INTERSECTION WITH DATE DRIVE. VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BIRCH CIRCLE, FROM INTERSECTION WITH DATE DRIVE. VIEW FACING WEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  16. VIEW OF ELM DRIVE FROM ITS INTERSECTION WITH ELM CIRCLE. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF ELM DRIVE FROM ITS INTERSECTION WITH ELM CIRCLE. VIEW FACING SOUTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  17. VIEW ACROSS BIRCH CIRCLE, SHOWING PLAYGROUND #1 NEAR DATE DRIVE. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW ACROSS BIRCH CIRCLE, SHOWING PLAYGROUND #1 NEAR DATE DRIVE. VIEW FACING NORTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  18. Effective Teaching Circles: Support for Math Anxious Students

    ERIC Educational Resources Information Center

    Powell, Mary Ann; Harrington, Judy

    2011-01-01

    Teaching circles are an innovative mechanism to support faculty and improve student learning. This article describes the use of instructor teaching circles to support math-anxious students at a mid-sized urban university, including the purposes, formation, and sometimes surprising outcomes associated with using this method. Teaching circles for…

  19. Multiple Intelligence Literature Circles: A JFL and an EFL Experience

    ERIC Educational Resources Information Center

    Sai, Michiko; Hsu, Jeng-yih

    2007-01-01

    The idea of literature circles is not new; however, it is hardly adapted in a second language classroom. In Taiwan, using literature circles to teach a second/foreign language is even less seen. The two college teachers-researchers reported their experiences of trying out literature circles in a JFL (Japanese as a Foreign Language) and an EFL…

  20. The Critique Circle: A Technique for Teaching Oral Performance Criticism.

    ERIC Educational Resources Information Center

    Hirvela, David P.

    The critique circle is a pedagogical technique for involving students in the process of oral evaluative criticism of performance work. After the performance of scenes, students gather in a circle. Any student may begin the critique and responses proceed around the circle in a clockwise fashion, with the rules requiring each student to evaluate or…

  1. VIEW OF FACILITY 628 ON BIRCH CIRCLE, ON THE CORNER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF FACILITY 628 ON BIRCH CIRCLE, ON THE CORNER OF CEDAR DRIVE AND BIRCH CIRCLE, ON THE NAVY SIDE OF THE NEIGHBORHOOD. VIEW FACING NORTH/NORTHWEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  2. The Acoustic Reality of the Kachruvian Circles: A Rhythmic Perspective

    ERIC Educational Resources Information Center

    Low, Ee Ling

    2010-01-01

    This paper investigates whether the rhythmic properties of varieties of English found in each of the concentric circles of Kachru's model can, in any way, be elucidated by the "Three Circles" model. A measurement and comparison of the rhythm of three varieties of English: British English (from the Inner Circle), Singapore English (from the Outer…

  3. A Spring Playscape Project: Building a Tree Circle

    ERIC Educational Resources Information Center

    Keeler, Rusty

    2009-01-01

    The Tree Circle is a green gathering area for children made by planting trees in a circle. For children, the Tree Circle becomes a magical place for dramatic play, quiet retreat, or lively nature exploration. For teachers and parents it becomes a shady grove for snacks and stories. The trees create a sweet spot that changes during the seasons and…

  4. Extra-chromosomal DNA maintenance in Bacillus subtilis, dependence on flagellation factor FliF and moonlighting mediator EdmS.

    PubMed

    Hakumai, Yuichi; Shimomoto, Kouko; Ashiuchi, Makoto

    2015-05-15

    Extra-chromosomal DNA maintenance (EDM) as an important process in the propagation and genetic engineering of microbes. Bacillus subtilis EdmS (formerly PgsE), a protein comprising 55 amino acids, is a mediator of the EDM process. In this study, the effect of mutation of global regulators on B. subtilis EDM was examined. Mutation of the swrA gene abolished EdmS-mediated EDM. It is known that swrA predominantly regulates expression of the fla/che operon in B. subtilis. We therefore performed EDM analysis using fla/che-deletion mutants and identified an EDM-mediated EDM cooperator in the flgB-fliL region. Further genetic investigation identified the flagellation factor FliF is a crucial EDM cooperator. To our knowledge, this is the first observation of the moonlighting function of FliF in DNA maintenance. PMID:25843804

  5. Distortion theorems for polynomials on a circle

    SciTech Connect

    Dubinin, V N

    2000-12-31

    Inequalities for the derivatives with respect to {phi}=arg z the functions ReP(z), |P(z)|{sup 2} and arg P(z) are established for an algebraic polynomial P(z) at points on the circle |z|=1. These estimates depend, in particular, on the constant term and the leading coefficient of the polynomial P(z) and improve the classical Bernstein and Turan inequalities. The method of proof is based on the techniques of generalized reduced moduli.

  6. Rolling circle amplification of metazoan mitochondrialgenomes

    SciTech Connect

    Simison, W. Brian; Lindberg, D.R.; Boore, J.L.

    2005-07-31

    Here we report the successful use of rolling circle amplification (RCA) for the amplification of complete metazoan mt genomes to make a product that is amenable to high-throughput genome sequencing techniques. The benefits of RCA over PCR are many and with further development and refinement of RCA, the sequencing of organellar genomics will require far less time and effort than current long PCR approaches.

  7. Walking in circles: a modelling approach

    PubMed Central

    Maus, Horst-Moritz; Seyfarth, Andre

    2014-01-01

    Blindfolded or disoriented people have the tendency to walk in circles rather than on a straight line even if they wanted to. Here, we use a minimalistic walking model to examine this phenomenon. The bipedal spring-loaded inverted pendulum exhibits asymptotically stable gaits with centre of mass (CoM) dynamics and ground reaction forces similar to human walking in the sagittal plane. We extend this model into three dimensions, and show that stable walking patterns persist if the leg is aligned with respect to the body (here: CoM velocity) instead of a world reference frame. Further, we demonstrate that asymmetric leg configurations, which are common in humans, will typically lead to walking in circles. The diameter of these circles depends strongly on parameter configuration, but is in line with empirical data from human walkers. Simulation results suggest that walking radius and especially direction of rotation are highly dependent on leg configuration and walking velocity, which explains inconsistent veering behaviour in repeated trials in human data. Finally, we discuss the relation between findings in the model and implications for human walking. PMID:25056215

  8. Walking in circles: a modelling approach.

    PubMed

    Maus, Horst-Moritz; Seyfarth, Andre

    2014-10-01

    Blindfolded or disoriented people have the tendency to walk in circles rather than on a straight line even if they wanted to. Here, we use a minimalistic walking model to examine this phenomenon. The bipedal spring-loaded inverted pendulum exhibits asymptotically stable gaits with centre of mass (CoM) dynamics and ground reaction forces similar to human walking in the sagittal plane. We extend this model into three dimensions, and show that stable walking patterns persist if the leg is aligned with respect to the body (here: CoM velocity) instead of a world reference frame. Further, we demonstrate that asymmetric leg configurations, which are common in humans, will typically lead to walking in circles. The diameter of these circles depends strongly on parameter configuration, but is in line with empirical data from human walkers. Simulation results suggest that walking radius and especially direction of rotation are highly dependent on leg configuration and walking velocity, which explains inconsistent veering behaviour in repeated trials in human data. Finally, we discuss the relation between findings in the model and implications for human walking. PMID:25056215

  9. A simple technique for morphological measurement of cerebral arterial circle variations using public domain software (Osiris).

    PubMed

    Ansari, Saeed; Dadmehr, Majid; Eftekhar, Behzad; McConnell, Douglas J; Ganji, Sarah; Azari, Hassan; Kamali-Ardakani, Shahab; Hoh, Brian L; Mocco, J

    2011-12-01

    This article describes a straightforward method to measure the dimensions and identify morphological variations in the cerebral arterial circle using the general-purpose software program Osiris. This user-friendly and portable program displays, manipulates, and analyzes medical digital images, and it has the capability to determine morphometric properties of selected blood vessels (or other anatomical structures) in humans and animals. To ascertain morphometric variations in the cerebral arterial circle, 132 brains of recently deceased fetuses, infants, and adults were dissected. The dissection procedure was first digitized, and then the dimensions were measured with Osiris software. Measurements of each vessel's length and external diameters were used to identify and classify morphological variations in the cerebral arterial circle. The most commonly observed anatomical variations were uni- and bilateral hypoplasia of the posterior communicating artery. This study demonstrates that public domain software can be used to measure and classify cerebral arterial circle vessels. This method could be extended to examine other anatomical regions or to study other animals. Additionally, knowledge of variations within the circle could be applied clinically to enhance diagnostic and treatment specificity. PMID:22254161

  10. The Life Cycle and Life Span of Namibian Fairy Circles

    PubMed Central

    Tschinkel, Walter R.

    2012-01-01

    In Namibia of southwestern Africa, the sparse grasslands that develop on deep sandy soils under rainfall between 50 and 100 mm per annum are punctuated by thousands of quasi-circular bare spots, usually surrounded by a ring of taller grass. The causes of these so-called “fairy circles” are unknown, although a number of hypotheses have been proposed. This paper provides a more complete description of the variation in size, density and attributes of fairy circles in a range of soil types and situations. Circles are not permanent; their vegetative and physical attributes allow them to be arranged into a life history sequence in which circles appear (birth), develop (mature) and become revegetated (die). Occasionally, they also enlarge. The appearance and disappearance of circles was confirmed from satellite images taken 4 years apart (2004, 2008). The frequency of births and deaths as a fraction of the total population of circles allowed the calculation of an approximate turnover rate, and from this, an estimate of circle lifespan. Lifespan appeared to vary with circle size, with small circles averaging about 24 years, and larger ones 43–75 years. Overall lifespan averaged about 41 yr. A second, independent estimate of lifespan was made by revisiting circles 2 to 9 years after their clear status had been confirmed. This resulted in a lifespan estimate of about 60 years. Any causal explanation of fairy circles must include their birth, development and death, their mean lifespan and the variation of their features under different conditions. PMID:22761663

  11. The rolling-circle melting-pot model for porcine circovirus DNA replication

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A stem-loop structure, formed by a pair of inverted repeats during DNA replication, is a conserved feature at the origin of DNA replication (Ori) among plant and animal viruses, bacteriophages and plasmids that replicate their genomes via the rolling-circle replication (RCR) mechanism. Porcine circo...

  12. Talking Circles, Leadership Competencies, and Inclusive Learning: Expanding the Frame of Business Education

    ERIC Educational Resources Information Center

    Cowan, David A.; Beard Adams, Kathy M.

    2008-01-01

    Business education typically embodies traditional organizational values, structures, and processes that focus learning mostly on uniformity and efficiency. In contrast, many First Nation peoples have long used the imagery of a circle as a guiding metaphor for both organizing and educating in ways that respect diversity and align themselves with…

  13. Infinite Maxwell fisheye inside a finite circle

    NASA Astrophysics Data System (ADS)

    Liu, Yangjié; Chen, Huanyang

    2015-12-01

    This manuscript proposes a two-dimensional heterogeneous imaging medium composed of an isotropic refractive index. We exploit conformal-mapping to transfer the full Maxwell fisheye into a finite circle. Unlike our previous design that requires a mirror of Zhukovski airfoil shape, this approach can work without a mirror, while offering a comparable imaging resolution. This medium may also be used as an isotropic gradient index lens to transform a light source inside it into two identical sources of null interference. A merit of this approach is reduction of the near-zero-index area from an infinite zone into a finite one, which shall ease its realization.

  14. Attributions of Quality Circles' Failure: Differences among Top Management, Supporting Staff, and Quality Circle Members.

    ERIC Educational Resources Information Center

    Tang, Thomas Li-Ping; Butler, Edie Aguilar

    For the past two decades, Japanese management practices have attracted a great deal of attention in the United States. Quality Circles (QCs) have been considered to be one of the most promising approaches to improving American workers' productivity. QCs are defined as small groups of employees from the same work area who meet to identify, analyze,…

  15. Expanding Circles within the Outer Circle: The Rural Kisii in Kenya

    ERIC Educational Resources Information Center

    Michieka, Martha M.

    2009-01-01

    This paper evaluates a range of factors that have contributed to the limited spread of English to rural Kisii, Kenya, making the presence of English in this non-urban context fall closer to an English as a Foreign Language (EFL) or Expanding Circle continuum than to the expected English as a Second Language (ESL) context. Kenya is an Outer Circle…

  16. Critical invariant circles in asymmetric and multiharmonic generalized standard maps

    NASA Astrophysics Data System (ADS)

    Fox, Adam M.; Meiss, James D.

    2014-04-01

    Invariant circles play an important role as barriers to transport in the dynamics of area-preserving maps. KAM theory guarantees the persistence of some circles for near-integrable maps, but far from the integrable case all circles can be destroyed. A standard method for determining the existence or nonexistence of a circle, Greene's residue criterion, requires the computation of long-period orbits, which can be difficult if the map has no reversing symmetry. We use de la Llave's quasi-Newton, Fourier-based scheme to numerically compute the conjugacy of a Diophantine circle conjugate to rigid rotation, and the singularity of a norm of a derivative of the conjugacy to predict criticality. We study near-critical conjugacies for families of rotational invariant circles in generalizations of Chirikov's standard map.

  17. The arithmetic of elliptic fibrations in gauge theories on a circle

    NASA Astrophysics Data System (ADS)

    Grimm, Thomas W.; Kapfer, Andreas; Klevers, Denis

    2016-06-01

    The geometry of elliptic fibrations translates to the physics of gauge theories in F-theory. We systematically develop the dictionary between arithmetic structures on elliptic curves as well as desingularized elliptic fibrations and symmetries of gauge theories on a circle. We show that the Mordell-Weil group law matches integral large gauge transformations around the circle in Abelian gauge theories and explain the significance of Mordell-Weil torsion in this context. We also use Higgs transitions and circle large gauge transformations to introduce a group law for genus-one fibrations with multi-sections. Finally, we introduce a novel arithmetic structure on elliptic fibrations with non-Abelian gauge groups in F-theory. It is defined on the set of exceptional divisors resolving the singularities and divisor classes of sections of the fibration. This group structure can be matched with certain integral non-Abelian large gauge transformations around the circle when studying the theory on the lower-dimensional Coulomb branch. Its existence is required by consistency with Higgs transitions from the non-Abelian theory to its Abelian phases in which it becomes the Mordell-Weil group. This hints towards the existence of a new underlying geometric symmetry.

  18. Existence of Chimera State on Two Parallel Circles

    NASA Astrophysics Data System (ADS)

    Lin, Larry; Yang, Pei-Kun

    2016-06-01

    A nonlocal coupling system with oscillators on two parallel circles can evolve into a chimera state for suitable values of the parameters α and β. The parameter β is the distance between the circles and affects the phase-locked areas of the chimera state. The Kuramoto theory successfully describes whether and where the oscillators are phase-locked or drifting. The position difference ΔX describes the displacement of phase-locked areas between the circles. The dynamics of the model with four oscillators also show similar phenomena. The position difference ΔX results from the arrangement of oscillators on the two parallel circles.

  19. GENERATING FRACTAL PATTERNS BY USING p-CIRCLE INVERSION

    NASA Astrophysics Data System (ADS)

    Ramírez, José L.; Rubiano, Gustavo N.; Zlobec, Borut Jurčič

    2015-10-01

    In this paper, we introduce the p-circle inversion which generalizes the classical inversion with respect to a circle (p = 2) and the taxicab inversion (p = 1). We study some basic properties and we also show the inversive images of some basic curves. We apply this new transformation to well-known fractals such as Sierpinski triangle, Koch curve, dragon curve, Fibonacci fractal, among others. Then we obtain new fractal patterns. Moreover, we generalize the method called circle inversion fractal be means of the p-circle inversion.

  20. General view, showing eastern view from atop hemi circle. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view, showing eastern view from atop hemi circle. - Arlington Memorial Bridge, Spanning Potomac River between Lincoln Memorial & Arlington National Cemetery, Washington, District of Columbia, DC

  1. Outer Circle Versus Inner Circle: Special Considerations While Rejuvenating an Indian Face Using Fillers

    PubMed Central

    Shetty, Rashmi

    2015-01-01

    Introduction: An oval face, pronounced cheek bones, a defined jaw line and a smooth Ogee curve are global aesthetic beauty goals. Though criteria are similar the Indian face poses some unique challenges because of the innate differences in skeletal shape, size, and soft tissue disposition. Width of the malar prominences and mandibular angles along with height are smaller compared to the other Asian and Caucasian populations along with a much heavier soft tissue disposition. This creates unique deficits and places unique demands on aesthetic intervention. Objectives: The evolution of practice patterns has lead to a variety of newer approaches; however, it is still common to target the nasolabial and mid-face volumizing as basic intervention for facial beautifying and rejuvenation. As aging progresses, Indian faces tend to get fuller and the tissue then descends downwards similar to other ethnic groups albeit more aggressive due to higher volumes of facial fat pad and smaller bone framework. Any excess correction in the inner circle zones will further add to the bulk along with cumulative remnants of previously administered fillers. Methods: In a younger face when the goal is beautification the attempt is to address the specific structural deficit on the outer bony framework along with the chin. This enhances the appearance immediately as well as holds up the tissue descent as they age. When the goal is youthful transition of an aging face, then again the bony changes further enhance the deficit in framework and the loss of fat pads along the periphery that is lateral forehead, temples and lateral cheek. Fat pad correction will give the most natural and best results as against working on the anterior mid cheek, nasolabials and angle of the mouth in a soft tissue heavy center zone of the face. Botulinum toxin and hyaluronic acid (HA) fillers remain the most popular facial injectables used for facial rejuvenation and structural enhancement. Results: Naturally enhanced

  2. No evidence for anomalously low variance circles on the sky

    SciTech Connect

    Moss, Adam; Scott, Douglas; Zibin, James P. E-mail: dscott@phas.ubc.ca

    2011-04-01

    In a recent paper, Gurzadyan and Penrose claim to have found directions on the sky centred on which are circles of anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular picture of the very early Universe. We attempted to repeat the analysis of these authors, and we can indeed confirm that such variations do exist in the temperature variance for annuli around points in the data. However, we find that this variation is entirely expected in a sky which contains the usual CMB anisotropies. In other words, properly simulated Gaussian CMB data contain just the sorts of variations claimed. Gurzadyan and Penrose have not found evidence for pre-Big Bang phenomena, but have simply re-discovered that the CMB contains structure.

  3. Collusive attacks to "circle-type" multi-party quantum key agreement protocols

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Xiao, Di; Jia, Heng-Yue; Liu, Run-Zong

    2016-05-01

    We find that existing multi-party quantum key agreement (MQKA) protocols designed for fairness of the key are, in fact, unfair. Our analysis shows that these protocols are sensitive to collusive attacks; that is, dishonest participants can collaborate in predetermining the key without being detected. In fact, the transmission structures of the quantum particles in those unfair MQKA protocols, three of which have already been analyzed, have much in common. We call these unfair MQKA protocols circle-type MQKA protocols. Likewise, the transmission structures of the quantum particles in MQKA protocols that can resist collusive attacks are also similar. We call such protocols complete-graph-type MQKA protocols. A MQKA protocol also exists that can resist the above attacks but is still not fair, and we call it the tree-type MQKA protocol. We first point out a common, easily missed loophole that severely compromises the fairness of present circle-type MQKA protocols. Then we show that two dishonest participants at special positions can totally predetermine the key generated by circle-type MQKA protocols. We anticipate that our observations will contribute to secure and fair MQKA protocols, especially circle-type protocols.

  4. Distribution of Circles on a Circle and Correlation Between Vortex Rings of Superfluids

    NASA Astrophysics Data System (ADS)

    Onur Fen, Mehmet; Erkoç, Šakír

    2007-05-01

    Superfluids are characterized by absence of viscosity. When superfluids are rotated, differently from normal fluids, they form more than one vortex in the containers where they are placed. The number of vortices change as the rotation velocity changes, but this change is not linear. M.W. Zwierlein et al. observed the vortices in experiments, observing up to a number of 80. Experiments also showed that the vortex distributions cannot include large spaces. By using experimental data, we noticed that when we think of vortices as vortex rings, their centers are at the same geometric location and these geometric locations are concentric circles. We generalized the distribution of these geometric places and formulized it. Our formula includes the magic circle numbers. When the number of vortices reach these magic numbers, the number of geometric locations increase by 1.

  5. Participation and Gender in Circle-Time Situations in Preschool

    ERIC Educational Resources Information Center

    Emilson, Anette; Johansson, Eva

    2013-01-01

    This study sought to investigate participatory values in relation to gender, as expressed in interactions between teachers and children in circle-time situations in Swedish and Norwegian preschools. This paper reports evidence from three research questions: How is children's participation conditioned in circle-time situations? How are…

  6. Quality Circles in Higher Education: Quality, Satisfaction, and Climate.

    ERIC Educational Resources Information Center

    Kay, Carol; Healy, Margaret

    The effect of quality circles at Iowa State University on absenteeism, performance evaluation, perceptions of the organization climate, job satisfaction, and perceived opportunities for professional and personal growth was measured in this study. The process of quality circles is designed to promote job fulfillment and organizational productivity…

  7. An Effective Time and Management Strategy in Quality Circles.

    ERIC Educational Resources Information Center

    Halverson, Don E.

    Contending that participation in quality circles enhances effective time management by school administrators and teachers, this guide provides both a theoretical briefing and practical recommendations for better time management. A pre- posttest prefaces a review of basic concepts of quality circles with reference to the work of Abraham Maslow,…

  8. VIEW OF THE OUTER RING OF CENTER CIRCLE, LOOKING NORTH. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF THE OUTER RING OF CENTER CIRCLE, LOOKING NORTH. GRANITE COPING DEFINES THE SWAIN FAMILY PLOT, WHICH CONTAINS A CELTIC CROSS, ON WHICH THE CIRCLE REFERS TO ETERNAL LIFE, AND A RECLINING HUMAN FIGURE IN ETERNAL SLEEP - Woodlands Cemetery, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA

  9. Growing a Circle of Courage Culture: One School's Journey

    ERIC Educational Resources Information Center

    Espiner, Deborah; Guild, Diane

    2010-01-01

    Mt. Richmond Special School is the first Circle of Courage school in New Zealand. The school reflects the richness of the cultural and learning diversity found in many New Zealand schools. Located in the heart of South Auckland, the school's 130 students represent a wide range of ethnic backgrounds. The universal values in the Circle of Courage…

  10. 29 CFR 1620.26 - Red circle rates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 4 2013-07-01 2013-07-01 false Red circle rates. 1620.26 Section 1620.26 Labor Regulations Relating to Labor (Continued) EQUAL EMPLOYMENT OPPORTUNITY COMMISSION THE EQUAL PAY ACT § 1620.26 Red circle rates. (a) The term “red circle” rate is used to describe certain unusual, higher than...

  11. The Japanese Quality Control Circle: Why It Works.

    ERIC Educational Resources Information Center

    Watanabe, Susumu

    1991-01-01

    The competitiveness of Japanese industry is in part because of their quality circles. Despite the West's interest in most Japanese business practices, quality circles have been difficult to transplant. This may be a result of misconceptions about their nature and the erroneous idea that workers' motivation is sociocultural, whereas in fact it is…

  12. DETAIL VIEW OF PIEDMONT AVENUE TRAFFIC CIRCLE AT INTERSECTION OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL VIEW OF PIEDMONT AVENUE TRAFFIC CIRCLE AT INTERSECTION OF CHANNING WAY. SEEN FROM EAST SIDE OF CIRCLE LOOKING NORTH AT 2395 PIEDMONT, SIGMA PI HOUSE BY FREDERICK H. REIMERS, 1928. Photograph by Brian Grogan, July 8, 2007 - Piedmont Way & the Berkeley Property Tract, East of College Avenue between Dwight Way & U.C. Memorial Stadium, Berkeley, Alameda County, CA

  13. Families and the Circle of Courage[TM

    ERIC Educational Resources Information Center

    Garfat, Thom; Van Bockern, Steve

    2010-01-01

    The Circle of Courage philosophy encourages thoughts about the importance of courage in the lives of children and young people--the courage to face what life offers and the resilience to handle life's challenges. Belonging, mastery, independence, and generosity, the four areas identified by the Circle of Courage, are pathways to help young people…

  14. VIEW OF BIRCH CIRCLE, SHOWING SEGMENT WHICH FORMS THE WESTERNMOST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BIRCH CIRCLE, SHOWING SEGMENT WHICH FORMS THE WESTERNMOST BOUNDARY OF THE NEIGHBORHOOD. VIEW FACING NORTH/NORTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  15. VIEW OF PLAYGROUND #4 NEAR ELM CIRCLE, SHOWING PICNIC TABLE. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF PLAYGROUND #4 NEAR ELM CIRCLE, SHOWING PICNIC TABLE. VIEW FACING EAST/NORTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  16. VIEW OF ELM CIRCLE, FROM BETWEEN FACILITIES 750 AND 750. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF ELM CIRCLE, FROM BETWEEN FACILITIES 750 AND 750. VIEW FACING EAST/NORTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  17. VIEW OF PLAYGROUND #3 ON SOUTHERN PORTION OF BIRCH CIRCLE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF PLAYGROUND #3 ON SOUTHERN PORTION OF BIRCH CIRCLE, SHOWING BENCH AND DRINKING FOUNTAIN. VIEW FACING NORTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  18. VIEW OF BIRCH CIRCLE FROM ITS INTERSECTION WITH CEDAR DRIVE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BIRCH CIRCLE FROM ITS INTERSECTION WITH CEDAR DRIVE, ON THE MARINE SIDE OF THE NEIGHBORHOOD. RESIDENTIAL TOWER VISIBLE ON FAR RIGHT. VIEW FACING EAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  19. VIEW OF BACKYARD AREA BEHIND FACILITIES 529 (BIRCH CIRCLE) AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BACKYARD AREA BEHIND FACILITIES 529 (BIRCH CIRCLE) AND 606 (CEDAR DRIVE). VIEW FACING SOUTHWEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  20. VIEW OF DATE DRIVE, FROM INTERSECTION WITH BIRCH CIRCLE, WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF DATE DRIVE, FROM INTERSECTION WITH BIRCH CIRCLE, WITH FACILITY 809 ON LEFT, 816 ON RIGHT. NOTE THE MANY DATE PALMS. VIEW FACING NORTHWEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  1. Study Circles and the Dialogue to Change Program

    ERIC Educational Resources Information Center

    Brennan, Mary; Brophy, Mark

    2010-01-01

    The origins of study circles can be traced back to the Chautauqua movement in the USA in the late nineteenth century. However, interest diminished in the USA and the Swedes discovered and enthusiastically imported the study circle idea as a remedy to their problems of poverty and illiteracy and to educate the broadest possible spectrum of society…

  2. From Skeptic to Believer: One Teacher's Journey Implementing Literature Circles

    ERIC Educational Resources Information Center

    Day, Deanna; Ainley, Glenna

    2008-01-01

    This is the story of one middle school teacher's journey of implementing literature circles with English language learners. Theory and research suggest that literature circles are valuable and important for young adolescents yet many teachers are still skeptical about implementing them. During this three-month study 22 sixth graders, 12 of them…

  3. The Sacred Circle: A Process Pedagogy of Healing.

    ERIC Educational Resources Information Center

    Regnier, Robert

    1994-01-01

    The process pedagogy proposed here, based on Canadian Plains Indians' Sacred Circle teaching and educational practices at an aboriginal high school, views healing as transition toward meaning, wholeness, connectedness, and balance. The paper examines Whitehead's criticism of western metaphysics, the Sacred Circle as expression of aboriginal…

  4. Empowerment of Children through Circle Time: Myth or Reality?

    ERIC Educational Resources Information Center

    Collins, Bernie

    2013-01-01

    The focus of this paper is circle time, a widely used method in primary schools in Ireland and elsewhere. It involves children sitting in a circle with their teacher using method-specific techniques and strategies for self-esteem enhancement, promoting positive relationships and development of social skills. Qualitative research was undertaken in…

  5. Quality Circles: Applications in Vocational Education. Information Series No. 249.

    ERIC Educational Resources Information Center

    Lloyd, Russell F.; Rehg, Virgil R.

    A strategy for increasing worker participation in an effort to remedy the problems of declining productivity and quality is the quality circles concept. The quality circles process involves small groups of employees who meet voluntarily on a regular basis to identify, analyze, and develop solutions to problems and to implement the solutions when…

  6. Conceptions and Representations: The Circle as an Example.

    ERIC Educational Resources Information Center

    Janvier, Claude

    This paper, which addresses the issue of representation as an internal construct corresponding to an external abstract configuration, attempts to extend A. A. DiSessa's phenomenological primitives to mathematics (particularly to the notion of circle). Various acceptations of the word representation are examined, using the notion of a circle as an…

  7. Using Social Psychology To Make Quality Circles More Effective.

    ERIC Educational Resources Information Center

    Smither, Robert D.

    Quality circles have proliferated in organizations throughout the 1980s, but their success depends on careful planning and monitoring, and on an awareness of social psychology and group dynamics. This presentation accordingly evaluates some of the assumptions of the literature on quality circles and suggests ways in which social psychology…

  8. Ethical dimension of circle Integrative Community Therapy on qualitative research.

    PubMed

    Santos, Paula Renata Miranda Dos; Cerencovich, Elisangela; Araújo, Laura Filomena Santos de; Bellato, Roseney; Maruyama, Sonia Ayako Tao

    2014-12-01

    This study discusses ethical issues in research involving human beings and seeks to understand the relationship between qualitative research and the ethical care guidelines for Integrative Community Therapy (ICT) circles based on Resolution 466/12 of the National Health Council of the Ministry of Health of Brazil. This is documentary research, which analyzed Resolution 466/12 and ICT circles seeking to make a connection between the ethical guidelines contained in both. The analysis of the corpus was directed toward the construction of the following results: the person's perception, cultural diversity and community. It also brings in consideration of the influence of the ethical dimension of the ICT circles on qualitative research. We conclude that ICT circles are innovative in the sense of the diversity of participants and respect for cultural and social differences. Thus, ICT circles promote acquisition of quality information for social research as well as compliance with the ethical guidelines outlined in Resolution No. 466/12. PMID:25830749

  9. Sleep disturbances and PTSD: a perpetual circle?

    PubMed Central

    van Liempt, Saskia

    2012-01-01

    Background Sleep facilitates the consolidation of fear extinction memory. Nightmares and insomnia are hallmark symptoms of posttraumatic stress disorder (PTSD), possibly interfering with fear extinction and compromising recovery. A perpetual circle may develop when sleep disturbances increase the risk for PTSD and vice versa. To date, therapeutic options for alleviating sleep disturbances in PTSD are limited. Methods We conducted three studies to examine the relationship between sleep and posttraumatic symptoms: (1) a prospective longitudinal cohort study examining the impact of pre-deployment insomnia symptoms and nightmares on the development of PTSD; (2) a cross-sectional study examining subjective sleep measures, polysomnography, endocrinological parameters, and memory in veterans with PTSD, veterans without PTSD, and healthy controls (HCs); (3) a randomized controlled trial (RCT) (n=14) comparing the effect of prazosin and placebo on sleep disturbances in veterans with PTSD. In addition to these studies, we systematically reviewed the literature on treatment options for sleep disturbances in PTSD. Results Pre-deployment nightmares predicted PTSD symptoms at 6 months post-deployment; however, insomnia symptoms did not. Furthermore, in patients with PTSD, a correlation between the apnea index and PTSD severity was observed, while obstructive sleep apnea syndrome was not more prevalent. We observed a significant increase in awakenings during sleep in patients with PTSD, which were positively correlated with adrenocorticotropic hormone (ACTH) levels, negatively correlated with growth hormone (GH) secretion, and the subjective perception of sleep depth. Also, heart rate was significantly increased in PTSD patients. Interestingly, plasma levels of GH during the night were decreased in PTSD. Furthermore, GH secretion and awakenings were independent predictors for delayed recall, which was lower in PTSD. In our RCT, prazosin was not associated with improvement of any

  10. Inhomogeneous field theory inside the arctic circle

    NASA Astrophysics Data System (ADS)

    Allegra, Nicolas; Dubail, Jérôme; Stéphan, Jean-Marie; Viti, Jacopo

    2016-05-01

    Motivated by quantum quenches in spin chains, a one-dimensional toy-model of fermionic particles evolving in imaginary-time from a domain-wall initial state is solved. The main interest of this toy-model is that it exhibits the arctic circle phenomenon, namely a spatial phase separation between a critically fluctuating region and a frozen region. Large-scale correlations inside the critical region are expressed in terms of correlators in a (euclidean) two-dimensional massless Dirac field theory. It is observed that this theory is inhomogenous: the metric is position-dependent, so it is in fact a Dirac theory in curved space. The technique used to solve the toy-model is then extended to deal with the transfer matrices of other models: dimers on the honeycomb and square lattice, and the six-vertex model at the free fermion point (Δ =0 ). In all cases, explicit expressions are given for the long-range correlations in the critical region, as well as for the underlying Dirac action. Although the setup developed here is heavily based on fermionic observables, the results can be translated into the language of height configurations and of the gaussian free field, via bosonization. Correlations close to the phase boundary and the generic appearance of Airy processes in all these models are also briefly revisited in the appendix.

  11. Controlled Microwave Heating Accelerates Rolling Circle Amplification

    PubMed Central

    Yoshimura, Takeo; Suzuki, Takamasa; Mineki, Shigeru; Ohuchi, Shokichi

    2015-01-01

    Rolling circle amplification (RCA) generates single-stranded DNAs or RNA, and the diverse applications of this isothermal technique range from the sensitive detection of nucleic acids to analysis of single nucleotide polymorphisms. Microwave chemistry is widely applied to increase reaction rate as well as product yield and purity. The objectives of the present research were to apply microwave heating to RCA and indicate factors that contribute to the microwave selective heating effect. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. Here, we showed that microwave-assisted RCA reactions catalyzed by either of the four thermostable DNA polymerases were accelerated over 4-folds compared with conventional RCA. Furthermore, the temperatures of the individual buffer components were specifically influenced by microwave heating. We concluded that microwave heating accelerated isothermal RCA of DNA because of the differential heating mechanisms of microwaves on the temperatures of reaction components, although the overall reaction temperatures were the same. PMID:26348227

  12. Continuous, Full-Circle Arctangent Circuit

    NASA Technical Reports Server (NTRS)

    Alhorn, Dean C.; Howard, David E.; Smith, Dennis A.

    2005-01-01

    A circuit generates an analog voltage proportional to an angle, in response to two sinusoidal input voltages having magnitudes proportional to the sine and cosine of the angle, respectively. That is to say, given input voltages proportional to sin(Omega(t))sin(Theta) and sin(Omega(t))cos(Theta) [where Theta denotes the angle, mega denotes 2(pi) x a carrier frequency, and t denotes time], the circuit generates a steady voltage proportional to Theta. The output voltage varies continuously from its minimum to its maximum value as Theta varies from -180deg to 180deg. While the circuit could accept input modulated sine and cosine signals from any source, it must be noted that such signals are typical of the outputs of shaft-angle resolvers in electromagnetic actuators used to measure and control shaft angles for diverse purposes like aiming scientific instruments and adjusting valve openings. In effect, the circuit is an analog computer that calculates the arctangent of the ratio between the sine and cosine signals. The full-circle angular range of this arctangent circuit stands in contrast to the range of prior analog arctangent circuits, which is from slightly greater than -90deg to slightly less than +90deg. Moreover, for applications in which continuous variation of output is preferred to discrete increments of output, this circuit offers a clear advantage over resolver- to-digital integrated circuits.

  13. General view, showing detail atop hemi circle at southern end ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view, showing detail atop hemi circle at southern end of Memorial Avenue. - Arlington Memorial Bridge, Spanning Potomac River between Lincoln Memorial & Arlington National Cemetery, Washington, District of Columbia, DC

  14. 6. Threequarter view of Awing, building 500, from Minuteman Circle ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Three-quarter view of A-wing, building 500, from Minuteman Circle looking northeast - Offutt Air Force Base, Strategic Air Command Headquarters & Command Center, Headquarters Building, 901 SAC Boulevard, Bellevue, Sarpy County, NE

  15. 7. VIEW NORTHWEST, OLD WHITE HORSE PIKE FORM CIRCLE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW NORTHWEST, OLD WHITE HORSE PIKE FORM CIRCLE - White Horse Pike Rond Point, Intersection of Crescent Boulevard (U.S. Route 130), White Horse Pike (U.S. Route 30), & Clay Avenue, Collingswood, Camden County, NJ

  16. Circles South East: the first 10 years 2002-2012.

    PubMed

    Bates, Andrew; Williams, Dominic; Wilson, Chris; Wilson, Robin J

    2014-07-01

    This article describes the first 10 years of the implementation of Circles of Support and Accountability (Circles) in the management of sexual offenders in South-East England by Circles South East (CSE). The Circles of 71 core members are reviewed in detail, with reference to demographic data, offense and sentencing histories, risk assessment data, and considerations regarding Multi-Agency Public Protection Arrangements. A group of 71 comparison subjects who were referred to CSE and deemed suitable for but did not receive the service was identified. Follow-up behaviors of both groups are examined (including all forms of reconviction, breach of orders, and prison recall). Over a comparable follow-up period of 55 months, the incidence of violent and contact sexual reconviction in the comparison group was significantly higher than for the Circles cohort. Comparisons are made between expected and actual levels of sexual reconviction, with the Circles cohort showing lower than expected rate of sexual reconviction but not to a statistically significant degree. PMID:23615793

  17. Maxi-circles, glycosomes, gene transposition, expression sites, transsplicing, transferrin receptors and base J.

    PubMed

    Borst, Piet

    2016-01-01

    This is a personal story of the author of his research on trypanosomatids, covering a period of 1970-2015. Some of the highlights include the discovery of new aspects of kDNA, the mini-circle heterogeneity and the maxi-circle; the glycosome; the discovery of gene transposition as a major mechanism for antigenic variation; trans-splicing as an essential step in the synthesis of all trypanosome mRNAs; Pulsed Field Gradient gels to size-fractionate chromosome-sized DNA molecules of protozoa; the sequence of trypanosome telomeres and their growth and contraction; the first ABC-transporter of trypanosomatids, LtpgpA; the variable transferrin receptor of T. brucei and its role in Fe uptake; and base J, its structure, biosynthesis and function. PMID:27021571

  18. Putting the Unit in Pre-Service Secondary Teachers' Unit Circle

    ERIC Educational Resources Information Center

    Moore, Kevin C.; LaForest, Kevin R.; Kim, Hee Jung

    2016-01-01

    We discuss a teaching experiment that explored two pre-service secondary teachers' meanings for the unit circle. Our analyses suggest that the participants' initial unit circle meanings predominantly consisted of calculational strategies for relating a given circle to what they called "the unit circle." These strategies did not entail…

  19. Three Concentric Circles: Young Chinese English Learners' Perceptions of Purposeful Audiences

    ERIC Educational Resources Information Center

    Liu, Jack Jinghui

    2015-01-01

    English learners have more access to communicate with different purposeful audiences across the Three Concentric Circles of English (Kachu, 1985): the Inner Circle, the Outer Circle and the Expanding Circle. However, young language learners' purposeful audience as a focus of communication has not been emphasized as much as other linguistic…

  20. Coal geology of the Northeast Circle area, McCone and Dawson counties, Montana

    USGS Publications Warehouse

    Wincentsen, Herbert

    1979-01-01

    The Northeast Circle area is in central McCone and northern Dawson Counties, northeastern Montana. The area encompasses about 940 square miles and has a maximum relief of greater than 1,000 feet. The lowest point (altitude of less than 2,200 feet) is in the Redwater River Valley in the northern part of the area. The highest point (altitude of less than 3,200 feet) is on the Yellowstone-Missouri divide, located in parts of Tps. 18 and 19 N., Rso 49, 50, and 51E., and T. 20 N., Rs. 52 and 53 E. Surface exposures in most of the area consist of yellowish or light-colored sandy shales of the Tongue River Member of the Paleocene Fort Union Formation. The coal beds in the Northeast Circle area occur in the lower 500 feet of this member and are persistent in the field. The predominant structural features of the area are the northeast end of the Weldon monocline-fault in Tps. 21 and 22 N., R. 47 E., and a small steep depression near Circle in sec. 10, T. 19 N., R. 48 E. Otherwise, the structure of the area is nearly flat. Coal in the Northeast Circle area is composed of six main beds: the S, L1, R, Q, P, and Pust beds, in ascending stratigraphic order. Of these, the S, Pust, and P beds are the thickest. The S bed is more than 20 feet thick in some places, but usually ranges in thickness from 6 to 10 feet. The Pust bed, which is about 430-490 feet above the S bed, is more than 18 feet thick in the upper bench and as much as 9 feet thick in the lower bench. Coal thickness in the P bed varies from 0 to 10.5 feet. The other coal seams in the area are generally less than 5 feet thick. All coals are lignite in rank.

  1. The Influence of Copy-Number of Targeted Extrachromosomal Genetic Elements on the Outcome of CRISPR-Cas Defense

    PubMed Central

    Severinov, Konstantin; Ispolatov, Iaroslav; Semenova, Ekaterina

    2016-01-01

    Prokaryotic type I CRISPR-Cas systems respond to the presence of mobile genetic elements such as plasmids and phages in two different ways. CRISPR interference efficiently destroys foreign DNA harboring protospacers fully matching CRISPR RNA spacers. In contrast, even a single mismatch between a spacer and a protospacer can render CRISPR interference ineffective but causes primed adaptation—efficient and specific acquisition of additional spacers from foreign DNA into the CRISPR array of the host. It has been proposed that the interference and primed adaptation pathways are mediated by structurally different complexes formed by the effector Cascade complex on matching and mismatched protospacers. Here, we present experimental evidence and present a simple mathematical model that shows that when plasmid copy number maintenance/phage genome replication is taken into account, the two apparently different outcomes of the CRISPR-Cas response can be accounted for by just one kind of effector complex on both targets. The results underscore the importance of consideration of targeted genome biology when considering consequences of CRISPR-Cas systems action.

  2. Circling behavior following unilateral kainic acid injections into rat striatum.

    PubMed

    Taylor, R J; Reavill, C; Jenner, P; Marsden, C D

    1981-12-01

    Unilateral injection of kainic acid (2.5-25 nmol) into rat anterior caudate putamen induced dose-related circling behaviour. Kainic acid (10 nmol) consistently caused initial weak ipsiversive circling lasting 1 h followed by prolonged strong contraversive rotation lasting in excess of 10 h. Unilateral intrastriatal administration of L-glutamic acid, or of monosodium L-glutamate, to normal rats, or administration of monosodium L-glutamate to rats with extensive decortication, did not induce circling behaviour. The simultaneous unilateral injection of monosodium L-glutamate (1 mumol) with kainic acid (10 nmol) did not modify circling behaviour induced by kainic acid. However, extensive decortication greatly reduced circling induced by unilateral intrastriatal kainic acid (10 nmol), and effect not reversed by the simultaneous administration of monosodium L-glutamate (1 mumol). Unilateral 6-hydroxydopamine lesions of the left nigrostriatal pathway abolished the initial ipsiversive rotation and potentiated the subsequent contraversive rotation for up to 4 h after intrastriatal injection of kainic acid (10 nmol). Peripheral administration of haloperidol (1 mg/kg i.p.) also abolished initial ipsiversive rotation and decreased the subsequent contraversive rotation. Electro-coagulation of the ipsilateral strio-nigral pathway prolonged the initial ipsiversive rotation produced by kainic acid, but markedly attenuated contraversive rotation. These findings suggest that circling induced by intrastriatal administration of kainic acid depends on intact corticostriate pathways, but it cannot be reproduced or modified by intrastriatal administration of glutamate. Kainic acid circling appears to be mediated via strio-nigral pathways, and to be modulated by dopaminergic function. PMID:7333356

  3. Circles of Support and personalization: Exploring the economic case.

    PubMed

    Wistow, Gerald; Perkins, Margaret; Knapp, Martin; Bauer, Annette; Bonin, Eva-Maria

    2016-06-01

    Circles of Support aim to enable people with learning disabilities (and others) to live full lives as part of their communities. As part of a wider study of the economic case for community capacity building conducted from 2012 to 2014, we conducted a mixed methods study of five Circles in North West England. Members of these Circles were supporting adults with moderate to profound learning disabilities and provided accounts of success in enabling the core member to live more independent lives with improved social care outcomes within cost envelopes that appeared to be less than more traditional types of support. The Circles also reported success in harnessing community resources to promote social inclusion and improve well-being. This very small-scale study can only offer tentative evidence but does appear to justify more rigorous research into the potential of Circles to secure cost-effective means of providing support to people with learning disabilities than the alternative, which in most cases would have been a long-term residential care placement. PMID:27004913

  4. Design of Circle Array Pattern for Transparent Nanomesh-Type Electrodes.

    PubMed

    Shin, Seungsu; Ganorkar, Shraddha; Kim, Jungyoon; Kim, Young-Hwan; Kim, Yong Tae; Kim, Seong-Il

    2015-10-01

    In this study, we report simulation results for the optical properties of nanomesh-type electrodes for transparent electrode. Usually, indium tin oxide (ITO) is commonly used for transparent conductor to solar cell, display, LED and other electronic modules. However, the cost is high due to the rarity of indium. An alternative way is use of transparent nanomesh-type metal electrode for solar cell. Finite different time domain (FDTD) method was used to simulate and analyze their optical properties. Various array patterns (square, circle and circle hexagonal array) of metal on glass (SiO2) substrates were designed and their properties of transmission and reflection were simulated by using the broad band (λ = 300~1200 nm) plane wave source. To compare basic characteristics of each pattern, various structural parameters such as hole diameter, pitch and metal thickness were applied. The effect of three typical metals, such as Ag, Au, and Al was also compared. In the results, we will discuss about large dip of transmission appeared at the particular wavelength region from the circle array pattern, which is design with pitch of 500 nm at the wavelength range 700 to 800 nm. The surface plasmonpolaritons (SPP) effect can be the cause of large dip and we could find a broad and high transmission from the properly designed in nanomesh-type electrodes, which was calculated as a function of wavelength. PMID:26726388

  5. Discovery of fairy circles in Australia supports self-organization theory.

    PubMed

    Getzin, Stephan; Yizhaq, Hezi; Bell, Bronwyn; Erickson, Todd E; Postle, Anthony C; Katra, Itzhak; Tzuk, Omer; Zelnik, Yuval R; Wiegand, Kerstin; Wiegand, Thorsten; Meron, Ehud

    2016-03-29

    Vegetation gap patterns in arid grasslands, such as the "fairy circles" of Namibia, are one of nature's greatest mysteries and subject to a lively debate on their origin. They are characterized by small-scale hexagonal ordering of circular bare-soil gaps that persists uniformly in the landscape scale to form a homogeneous distribution. Pattern-formation theory predicts that such highly ordered gap patterns should be found also in other water-limited systems across the globe, even if the mechanisms of their formation are different. Here we report that so far unknown fairy circles with the same spatial structure exist 10,000 km away from Namibia in the remote outback of Australia. Combining fieldwork, remote sensing, spatial pattern analysis, and process-based mathematical modeling, we demonstrate that these patterns emerge by self-organization, with no correlation with termite activity; the driving mechanism is a positive biomass-water feedback associated with water runoff and biomass-dependent infiltration rates. The remarkable match between the patterns of Australian and Namibian fairy circles and model results indicate that both patterns emerge from a nonuniform stationary instability, supporting a central universality principle of pattern-formation theory. Applied to the context of dryland vegetation, this principle predicts that different systems that go through the same instability type will show similar vegetation patterns even if the feedback mechanisms and resulting soil-water distributions are different, as we indeed found by comparing the Australian and the Namibian fairy-circle ecosystems. These results suggest that biomass-water feedbacks and resultant vegetation gap patterns are likely more common in remote drylands than is currently known. PMID:26976567

  6. An efficient circle detector not relying on edge detection

    NASA Astrophysics Data System (ADS)

    Cai, Jia; Huang, Panfeng; Chen, Lu; Zhang, Bin

    2016-06-01

    Accurate and efficient detection of circular modules fixed on non-cooperative target is a key technology for Tethered Space Robot. This paper presents an efficient circle detector based on region-growing of gradient and histogram distribution of Euclidean distance. Region-growing of gradient is applied to generate arc support regions from single point. And the corresponding square fitting areas are defined to accelerate the detection and decrease storage. A histogram is then used to count frequency of the distances that participates in the accumulator and the parameters of each circle are acquired. Finally, a verification strategy of circular integrity is designed to test the detection results. We have tested our algorithm on 35 images dealing with kinds of circles and ellipses. Experimental results demonstrate that our method is able to detect circular objects under occlusion, image noises and moderate shape deformations with a good precision.

  7. The Circle of Apollonius and Its Applications in Introductory Physics

    NASA Astrophysics Data System (ADS)

    Partensky, Michael B.

    2008-02-01

    The circle of Apollonius is named after the ancient geometrician Apollonius of Perga. This beautiful geometric construct can be helpful when solving some general problems of geometry and mathematical physics, optics, and electricity. Here we discuss two of its applications: localizing an object in space and calculating electric fields. First, we pose an entertaining localization problem to trigger students' interest in the subject. Analyzing this problem, we introduce the circle of Apollonius and show that this geometric technique helps solve the problem in an elegant and intuitive manner. Then we switch to seemingly unrelated problems of calculating the electric fields. We show that the zero equipotential line for two unlike charges is the Apollonius circle for these two charges and use this discovery to find the electric field of a charge positioned near a grounded conductive sphere. Finally, we pose some questions for further examination.

  8. Easing The Calculation Of Bolt-Circle Coordinates

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1995-01-01

    Bolt Circle Calculation (BOLT-CALC) computer program used to reduce significant time consumed in manually computing trigonometry of rectangular Cartesian coordinates of holes in bolt circle as shown on blueprint or drawing. Eliminates risk of computational errors, particularly in cases involving many holes or in cases in which coordinates expressed to many significant digits. Program assists in many practical situations arising in machine shops. Written in BASIC. Also successfully compiled and implemented by use of Microsoft's QuickBasic v4.0.

  9. A Phase Transition for Circle Maps and Cherry Flows

    NASA Astrophysics Data System (ADS)

    Palmisano, Liviana

    2013-07-01

    We study C 2 weakly order preserving circle maps with a flat interval. The main result of the paper is about a sharp transition from degenerate geometry to bounded geometry depending on the degree of the singularities at the boundary of the flat interval. We prove that the non-wandering set has zero Hausdorff dimension in the case of degenerate geometry and it has Hausdorff dimension strictly greater than zero in the case of bounded geometry. Our results about circle maps allow to establish a sharp phase transition in the dynamics of Cherry flows.

  10. Marrying Heterogeneous Circles of Trust: No Silver Bullet Yet

    NASA Astrophysics Data System (ADS)

    Ates, Mikaël; Gravier, Christophe; Fayolle, Jacques; Sauviac, Bruno

    2008-11-01

    Numerous business and state-owned entities assert the need of secured information exchanges on digital identities based on trusted third parties. Entities trusting each other create a federation. At first, it is necessary for them to formalize this alliance with legal documents. In a second time, an architecture of identity federation will allow them to establish technical trust links, creating a circle of trust, most often with a public key infrastructure. The real challenge for the identity federation domain is the interoperability of information systems thanks to normalized and standardized protocols, that is to say, realize interconnection of circles of trust.

  11. Computing circles and spheres of arithmitic least squares

    NASA Astrophysics Data System (ADS)

    Nievergelt, Yves

    1994-07-01

    A proof of the existence and uniqueness of L. Moura and R. Kitney's circle of least squares leads to estimates of the accuracy with which a computer can determine that circle. The result shows that the accuracy deteriorates as the correlation between the coordinates of the data points increases in magnitude. Yet a numerically more stable computation of eigenvectors yields the limiting straight line, which a further analysis reveals to be the line of total least squares. The same analysis also provides generalizations to fitting spheres in higher dimensions.

  12. Toroidal Single Wall Carbon Nanotubes in Fullerene Crop Circles

    NASA Technical Reports Server (NTRS)

    Han, Jie; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    We investigate energetics and structure of circular and polygonal single wall carbon nanotubes (SWNTs) using large scale molecular simulations on NAS SP2, motivated by their unusual electronic and magnetic properties. The circular tori are formed by bending tube (no net whereas the polygonal tori are constructed by turning the joint of two tubes of (n, n), (n+1, n-1) and (n+2, n-2) with topological pentagon-heptagon defect, in which n =5, 8 and 10. The strain energy of circular tori relative to straight tube decreases by I/D(sup 2) where D is torus diameter. As D increases, these tori change from buckling to an energetically stable state. The stable tori are perfect circular in both toroidal and tubular geometry with strain less than 0. 03 eV/atom when D greater than 10, 20 and 40 nm for torus (5,5), (8,8) and (10, 10). Polygonal tori, whose strain is proportional to the number of defects and I/D are energetically stable even for D less than 10 nm. However, their strain is higher than that of perfect circular tori. In addition, the local maximum strain of polygonal tori is much higher than that of perfect circular tori. It is approx. 0.03 eV/atom or less for perfect circular torus (5,5), but 0.13 and 0.21 eV/atom for polygonal tori (6,4)/(5,5) and (7,3)/(5,5). Therefore, we conclude that the circular tori with no topological defects are more energetically stable and kinetically accessible than the polygonal tori containing the pentagon-heptagon defects for the laser-grown SWNTs and Fullerene crop circles.

  13. Production of dumbbell probe through hairpin cleavage-ligation and increasing RCA sensitivity and specificity by circle to circle amplification

    PubMed Central

    Wei, Hua; Tang, Suming; Hu, Tianyu; Zhao, Guojie; Guan, Yifu

    2016-01-01

    Dumbbell probe (DP) attracts increasing interests in rolling circle amplification (RCA). A universal DP production method through cleavage-ligation of hairpin was proposed and optimized. The production is characterized by restriction endonuclease (RE)-induced cleavage ends ligation. It has the advantage of phosphorylation-free, splint-free and purification-free. To optimize designing, we found that the position of RE cleavage sequence in the stem and the primer position in the loop affected the formation and amplification of DP obviously. Both sticky and blunt ends cleaved by RE produce DP efficiently. Moreover, we introduced this DP into circle to circle (C2C) RCA based on the same cleavage-ligation principle, and acquired high sensitivity. By combining a two-ligation design and the C2C strategy, specificity for detecting let-7 family members was increased extremely. Furthermore, coreaction of different steps facilitated convenient formation and amplification process of DP. PMID:27385060

  14. Full Circle: A New Look at Multiage Education.

    ERIC Educational Resources Information Center

    Chase, Penelle; Doan, Jane

    Noting that there is a great demand for information to help educators learn about and develop programs in multiage education, this book shares many ideas on multiage instruction. The 12 chapters of the book are: (1) "Circling Back" (Jane Doan), on the resurgence of interest in the multiage movement; (2) "One Day" (Penelle Chase), exploring a day…

  15. The Circle of Courage and Erikson's Psychological Stages.

    ERIC Educational Resources Information Center

    Coughlan, Felicity; Welsh-Breetzke, Andrea

    2002-01-01

    Describes the application of positive youth development principles to challenges faced by adolescent females in South Africa. A mainline, Euro-centric theory, Erikson's life stages (1963), is compared with the Circle of Courage model based on Native American Tribal wisdom. The differences and correlation in these approaches are explored through…

  16. VIEW OF PIEDMONT AVENUE TRAFFIC CIRCLE AT INTERSECTION OF CHANNING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF PIEDMONT AVENUE TRAFFIC CIRCLE AT INTERSECTION OF CHANNING WAY VIEW OF 2401 PIEDMONT, ALPHA EPSILON PHI HOUSE BY RATCLIFF & RATCLIFF, 1958. SEEN FROM NW CORNER LOOKING SE. Photograph by Brian Grogan, July 8, 2007 - Piedmont Way & the Berkeley Property Tract, East of College Avenue between Dwight Way & U.C. Memorial Stadium, Berkeley, Alameda County, CA

  17. The Sharing Circle: Themes for Home and School Involvement.

    ERIC Educational Resources Information Center

    Spangler, Carol

    This guide describes a program that turns ordinary show-and-tell time into a theme-related sharing time, or "sharing circle." In this program, each child is assigned a special sharing day once a month, with the sharing days evenly distributed throughout the month and with no more than three children sharing on a particular day. Monthly themes are…

  18. The Misuse of the Circle Notation to Represent Aromatic Rings.

    ERIC Educational Resources Information Center

    Belloli, Robert C.

    1983-01-01

    Discusses the confusion and erroneous conclusions that can result from the overuse and misuse of the circle notation to represent aromaticity in polycylic aromatic hydrocarbons. Includes nature of the problem, textbook treatment, and a possible compromise method of representation. (Author/JN)

  19. Revisiting Cyberbullying in Schools Using the Quality Circle Approach

    ERIC Educational Resources Information Center

    Paul, Simone; Smith, Peter K.; Blumberg, Herbert H.

    2012-01-01

    An earlier study reported the use of Quality Circles (QC) in a UK school in the context of understanding and reducing bullying and cyberbullying. Here, we report further work in the same school setting. The QC approach allows explorative analysis of problems in school settings, whereby students embark on a problem-solving exercise over a period of…

  20. The Circle of Apollonius and Its Applications in Introductory Physics

    ERIC Educational Resources Information Center

    Partensky, Michael B.

    2008-01-01

    The circle of Apollonius is named after the ancient geometrician Apollonius of Perga. This beautiful geometric construct can be helpful when solving some general problems of geometry and mathematical physics, optics, and electricity. Here we discuss two of its applications: localizing an object in space and calculating electric fields. First, we…

  1. School of Urban Wilderness Survival and the Circle of Courage

    ERIC Educational Resources Information Center

    Marlowe, Jay M.; Pearl, Nick L.; Marlowe, Mike J.

    2009-01-01

    Brendtro, Brokenleg, and Van Bockern (2002) describe the Circle of Courage model for creating environments in which all children can thrive. This approach blends youth developmental research, the wisdom of pioneer workers, and Native American philosophies of child care. This model for reclaiming youth at risk posits four elements as essential for…

  2. Reading without Teachers: Literature Circles in an EFL Classroom

    ERIC Educational Resources Information Center

    Hsu, Jeng-yih Tim

    2004-01-01

    Unsuccessful college education often turns our students into book haters who will stop reading as soon as they graduate. The idea of literature circles embraces the concept of "reading for fun" and is intended to create more independent readers and book addicts who will continuously read for the rest of their lives. Pioneers in literacy theories…

  3. The 2004 Presidential Election and Young Voters. CIRCLE Fact Sheet.

    ERIC Educational Resources Information Center

    Center for Information and Research on Civic Learning and Engagement, 2004

    2004-01-01

    Young people?s interest in the 2004 presidential election is at its highest since 1992. According to a September MTV/The Center for Information & Research on Civic Learning & Engagement (CIRCLE) poll conducted by CBS News, 81 percent of young registered voters are paying close attention to the campaign, compared to 85 percent in 1992, the last…

  4. Novice Teachers Learn About Literature Circles through Collaborative Action Research.

    ERIC Educational Resources Information Center

    Davis, Barbara H.; Resta, Virginia; Davis, Laura L.; Camacho, Alexa

    2001-01-01

    Suggests that literature circles can provide a stimulating and motivating method of teaching reading, and they help increase student reading performance as measured on a criterion-referenced test. Notes that when students participate in literature discussion groups their reading level and motivation can increase. (SG)

  5. The Characterizations of Triangles Using the Nine-Point Circles

    ERIC Educational Resources Information Center

    Srinivasan, V. K.

    2012-01-01

    In this note, primarily intended for high school students and high school teachers, characterizations of a right triangle and an equilateral triangle in the Euclidean plane are presented using the nine-point circle of a given triangle. Geometrical applications are explored along with their possible uses in the teaching environment. (Contains 4…

  6. VIEW OF PIEDMONT AVENUE TRAFFIC CIRCLE AT INTERSECTION OF CHANNING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF PIEDMONT AVENUE TRAFFIC CIRCLE AT INTERSECTION OF CHANNING WAY. SEEN FROM SW CORNER TOWARDS 2395 PIEDMONT, SIGMA PI HOUSE BY FREDERICK H. REIMERS, 1928. LOOKING NORTH. Photograph by Brian Grogan, July 8, 2007 - Piedmont Way & the Berkeley Property Tract, East of College Avenue between Dwight Way & U.C. Memorial Stadium, Berkeley, Alameda County, CA

  7. VIEW OF PIEDMONT AVENUE TRAFFIC CIRCLE AT INTERSECTION OF CHANNING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF PIEDMONT AVENUE TRAFFIC CIRCLE AT INTERSECTION OF CHANNING WAY. SEEN FROM NE CORNER LOOKING SW. Photograph by Fredrica Drotos and Michael Kelly, July 9, 2006 - Piedmont Way & the Berkeley Property Tract, East of College Avenue between Dwight Way & U.C. Memorial Stadium, Berkeley, Alameda County, CA

  8. First Nations Education in Canada: The Circle Unfolds.

    ERIC Educational Resources Information Center

    Battiste, Marie, Ed.; Barman, Jean, Ed.

    This collection of 15 writings by Aboriginal and non-Aboriginal educators examines the issues and dilemmas of First Nations education in Canada 25 years after the beginnings of First Nations control of education. Organized around the concept of the Sacred Circle, the essays are grouped into four sections: reconceptualizing First Nations education,…

  9. A Paradigm Shift to Reading around the Hermeneutic Circle.

    ERIC Educational Resources Information Center

    Sparks, Elizabeth E.

    The background, challenge, opportunity, and excitement of hermeneutics can be explored in three signposts of a hermeneutic turn in a doctoral research proposal: from being gifted to gifted reading, from method to interpretation, and from metacognition to the hermeneutic circle. A change in the research site of a study of the metacognitive…

  10. Maximum-likelihood estimation of circle parameters via convolution.

    PubMed

    Zelniker, Emanuel E; Clarkson, I Vaughan L

    2006-04-01

    The accurate fitting of a circle to noisy measurements of circumferential points is a much studied problem in the literature. In this paper, we present an interpretation of the maximum-likelihood estimator (MLE) and the Delogne-Kåsa estimator (DKE) for circle-center and radius estimation in terms of convolution on an image which is ideal in a certain sense. We use our convolution-based MLE approach to find good estimates for the parameters of a circle in digital images. In digital images, it is then possible to treat these estimates as preliminary estimates into various other numerical techniques which further refine them to achieve subpixel accuracy. We also investigate the relationship between the convolution of an ideal image with a "phase-coded kernel" (PCK) and the MLE. This is related to the "phase-coded annulus" which was introduced by Atherton and Kerbyson who proposed it as one of a number of new convolution kernels for estimating circle center and radius. We show that the PCK is an approximate MLE (AMLE). We compare our AMLE method to the MLE and the DKE as well as the Cramér-Rao Lower Bound in ideal images and in both real and synthetic digital images. PMID:16579374

  11. Examining Circle of Security™: A Review of Research and Theory

    ERIC Educational Resources Information Center

    Mercer, Jean

    2015-01-01

    The Circle of Security™ interventions are psychosocial treatments intended to increase maternal sensitivity and thus child attachment security in infants and young children. A small number of publications have reported empirical research on outcomes of these treatments. This article reviews the research evidence, plausibility, theoretical…

  12. Literature Circles: A Perfect Match for Online Instruction

    ERIC Educational Resources Information Center

    Whittingham, Jeff

    2013-01-01

    This article describes the author's search for an appropriate and satisfying online teaching method. After experimenting with several methods (chat room, discussion board, student led discussion), the author reached back to his face-to-face classroom success with literature circles. This article reports the results of research conducted by the…

  13. Circle Time for Social and Emotional Learning in Primary School

    ERIC Educational Resources Information Center

    Cefai, Carmel; Ferrario, Erika; Cavioni, Valeria; Carter, Audrey; Grech, Tracy

    2014-01-01

    This paper discusses the findings and implications of a semi-randomised control trial study on the effectiveness of circle time (CT) on primary school students' social and emotional learning, as well as classroom teachers' and students' experience of CT. A social and emotional learning programme was delivered through CT by trained…

  14. The Study Circle--For Learning and Democracy

    ERIC Educational Resources Information Center

    Bjerkaker, Sturla

    2006-01-01

    The study circle is described as a democratic and emancipatory method for learning that can be summarized in three words: learning by sharing. This method offers opportunities and possibilities for all participants to contribute their previous knowledge and experiences through open and democratic dialogue. As a method for "liberal adult…

  15. Using Literature Circles to Discuss Social Justice in Teacher Education

    ERIC Educational Resources Information Center

    Madhuri, Marga; Walker, Nancy; Landmann-Johnsey, Erica; Laughter, Judson

    2015-01-01

    Literacy educators feel it is incumbent on teacher preparation programs to prepare teacher candidates with the dispositions and competencies needed to work with students from diverse racial, cultural, and economic backgrounds. As a way to initiate the discussion and help candidates examine their own views on race, literature circles are used. The…

  16. Sacred Circles: 2000 Years of North American Indian Art

    ERIC Educational Resources Information Center

    Journal of American Indian Education, 1977

    1977-01-01

    "Sacred Circles" opened April 16, 1977 at the Nelson Gallery of Art-Atkins Museum of Fine Arts in Kansas City for its only showing in the Americas; the 850 objects on loan from 90 museums and private collectors included the "Adena Pipe" (considered the most important archaeological object found in the eastern US). (JC)

  17. Intersections of a Circle and a Square: An Investigation

    ERIC Educational Resources Information Center

    Canada, Dan; Blair, Stephen

    2007-01-01

    The investigation of how a circle and square lying in the same plane could intersect each other is an excellent example of geometric problem-solving. This paper explores three facets of the investigation: (1) finding out how many points of intersection are possible, (2) classifying the different ways of intersection, and (3) determining which ways…

  18. United States Participation in the Pacific Circle Consortium. Final Report.

    ERIC Educational Resources Information Center

    Northwest Regional Educational Lab., Portland, OR.

    The goal of the Pacific Circle Project is to improve international and intercultural understanding among the people and nations of the Pacific. Consortium member countries are Australia, Canada, New Zealand, and the United States. Within the countries are chosen member institutions. Two major types of activities of the consortium are the exchange…

  19. Innovation and Organizational Communication in Corporate America: The Rhetorical Visions of Managers, Facilitators, and Employees on Quality Circles.

    ERIC Educational Resources Information Center

    Eyo, Bassey A.

    1992-01-01

    Examines the dynamics of organizational communication following corporate implementation of quality circles. Describes the rhetorical visions of people at three organizational levels closely associated with quality circles: (1) managers; (2) facilitators who organize the quality circles; and (3) employees. (SR)

  20. Late Mousterian persistence near the Arctic Circle.

    PubMed

    Slimak, Ludovic; Svendsen, John Inge; Mangerud, Jan; Plisson, Hugues; Heggen, Herbjørn Presthus; Brugère, Alexis; Pavlov, Pavel Yurievich

    2011-05-13

    Palaeolithic sites in Russian high latitudes have been considered as Upper Palaeolithic and thus representing an Arctic expansion of modern humans. Here we show that at Byzovaya, in the western foothills of the Polar Urals, the technological structure of the lithic assemblage makes it directly comparable with Mousterian Middle Palaeolithic industries that so far have been exclusively attributed to the Neandertal populations in Europe. Radiocarbon and optical-stimulated luminescence dates on bones and sand grains indicate that the site was occupied during a short period around 28,500 carbon-14 years before the present (about 31,000 to 34,000 calendar years ago), at the time when only Upper Palaeolithic cultures occupied lower latitudes of Eurasia. Byzovaya may thus represent a late northern refuge for Neandertals, about 1000 km north of earlier known Mousterian sites. PMID:21566192

  1. "Vicious circles": the development of morbid obesity.

    PubMed

    Owen-Smith, Amanda; Donovan, Jenny; Coast, Joanna

    2014-09-01

    Although there has been extensive research around the etiology of moderate obesity, there are still important questions relating to the development and lived experience of extreme obesity. We present a synthesis of data from two in-depth qualitative studies in which morbidly obese participants (N = 31) were able to explain the development of the condition in their own terms. We identified consistent themes in the two datasets, and undertook a detailed data synthesis. Particularly salient themes in the development of morbid obesity related to family structures and early socialization experiences, and the role of emotional distress was dominant in both initial weight gain and ongoing cycles of loss and regain. All informants accepted some responsibility for their health state, but identified a number of mitigating factors that limited personal culpability that were often related to the fulfillment of gendered social expectations. PMID:25079501

  2. Topographic control of sorted circle morphology on Svalbard

    NASA Astrophysics Data System (ADS)

    Voigt, Joana; Hauber, Ernst; Reiss, Dennis; Hiesinger, Harald; Johnsson, Andreas; van Gasselt, Stephan; Balme, Matt; Head, Jim; de Verra, Jean-Pierre; Steinbrügge, Gregor; Jaumann, Ralf

    2015-04-01

    Patterned ground is a typical phenomenon in polar, subpolar and alpine regions [1]. As it is commonly (but not necessarily!) related to freeze-thaw cycles, its presence on Mars could possibly point to locations and periods where and when liquid water existed in the recent past [2]. Sorted circles are a class of patterned ground that was tentatively identified in Elysium Planitia (Mars) [3], but this interpretation has been challenged on the basis of physical considerations [4]. Without direct access to potential patterned ground on Mars, the analysis of terrestrial analogues can inform the interpretation of Martian landforms. Svalbard (Norway) offers a wide variety of permafrost features that are morphologically analogous to Martian cold-climate landforms [5]. It hosts some of the best examples of sorted circles on Earth, which are located on the westernmost tip of Brøgger peninsula, on a broad strand flat that is characterized by a series of postglacial beach ridges [6]. Here we report on our analysis of sorted circle morphology (especially their plan-view shape, i.e. their "roundness" or ellipticity) and its correlation with local topography (slopes, curvature). Sorted circle morphology was determined from HRSC-AX images (for details on the flight campaign and image properties see ref [5]) and through field work. Topographic information comes from a 50 cm gridded DEM derived from HRSC-AX stereo images. We measured sorted circle morphology (ellipticity, azimuth of major axis) along a WNW-ESE traverse that runs from the inland towards the sea and is oriented perpendicular to the local beach ridge trend. Selected areas with homogeneous sorted circle appearance were visually mapped, and compared to the average slope, aspect, and the calculated topographic wetness index (TWI). Furthermore the whole traverse was classified into four different morphologies of the sorted patterned ground (sorted circles, sorted "ellipses", sorted nets and areas without patterned ground

  3. From EUCLID to Ptolemy in English Crop Circles

    NASA Astrophysics Data System (ADS)

    Hawkins, G. S.

    1997-12-01

    The late Lord Soli Zuckerman, science advisor to several British governments, encouraged the author, an astronomer, to test the theory that all crop circles were made by hoaxers. Within the hundreds of formations in Southern England he saw a thread of surprising historical content at the intellectual level of College Dons. One diagram in celestial mechanics involved triple conjunctions of Mercury, Venus and Mars every 67 2/3 years. Ptolemy's fourth musical scale, tense diatonic, occurred in the circles during the period 1978-88. Starting on E, Ptolemaic ratios make our perfect diatonic scale of white notes on the keyboard of the piano or church organ. For separated circles the ratio was given by diameters, and for concentric circles it was diameters squared. A series of rotationally symmetric figures began in 1988 which combined Ptolemy's ratios with Euclid's theorems. In his last plane theorem, Euclid (Elements 13,12) proved that the square on the side of an equilateral triangle is 3 times the square on the circum-circle radius -- diatonic note G(2). From the 1988 figure one can prove the square on the side is 16/3 times the square on the semi-altitude, giving note F(3). Later rotational figures over the next 5 years led to diatonic ratios for the hexagon, square and triangle. They gave with the exactness of Euclidean theorems the notes F, C(2) and E(2), and they are the only regular polygons to do so. Although these 4 crop theorems derive from Euclid, they were previously unknown as a set in the literature, nor had the Ptolemaic connection been published. Professional magazines asked the readers to provide a fifth theorem that would generate the above 4 theorems, but none was forthcoming. Ultimately the cicle makers showed knowledge of this generating theorem using a 200-ft design at Litchfield, Hampshire. After 1993, rotationally symmetric geometries continued to appear, but with much more complicated patterns. One design showed 6 crescent moons in a hexagon

  4. Calculation of Latitude and Longitude for Points on Perimeter of a Circle on a Sphere

    SciTech Connect

    Morris, Heidi E.

    2015-08-14

    This document describes the calculation of the Earth-Centered Earth Fixed (ECEF) coordinates for points lying on the perimeter of a circle. Here, the perimeter of the circle lies on the surface of the sphere and the center of the planar circle is below the surface. These coordinates are converted to latitude and longitude for mapping fields on the surface of the earth.

  5. The Chicken and the Egg: Inviting Response and Talk through Socratic Circles

    ERIC Educational Resources Information Center

    Styslinger, Mary E.; Pollock, Timothy

    2010-01-01

    This collaborative inquiry answers the following questions: 1) What is the nature of talk during Socratic Circles? 2) What is student response to talk? 3) How might knowing more about student response to talk and the nature of talk improve teaching during Socratic Circles? The article first describes the process of implementing Socratic Circles,…

  6. Expanding the Reach of Extension to Underserved Audiences through Study Circles in Rural Idaho

    ERIC Educational Resources Information Center

    Cummins, Melissa; Petty, Barbara; Hansen, Lyle; Hoffman, Katie; Wittman, Grace

    2012-01-01

    Extension educators expanded the reach of their programming to underserved audiences through the implementation of Study Circles in rural Southern Idaho. Study Circles gave educators entry into communities by establishing relationships necessary for long-term change. Study Circle discussions in rural Southern Idaho led to stronger relationships…

  7. Getting Started with Literature Circles. The Bill Harp Professional Teachers Library Series.

    ERIC Educational Resources Information Center

    Noe, Katherine L. Schlick; Johnson, Nancy J.

    Designed to help teachers get started using literature circles in their classrooms, this book gives teachers a boost to begin, offers some insights from other teachers, and helps teachers clarify where to go next. It notes that literature circles (or literature study groups, book clubs, or discussion circles) take many forms and engage students in…

  8. Around the CIRCLE: Research and Practice. Volume 5, Number 1, Fall 2007

    ERIC Educational Resources Information Center

    Center for Information and Research on Civic Learning and Engagement (CIRCLE), 2007

    2007-01-01

    The Center for Information and Research on Civic Learning and Engagement (CIRCLE) promotes research on the civic and political engagements of Americans between the ages of 15 and 25. The following topics are covered in this issue of "Around the CIRCLE": (1) Common Social Studies Teaching Practices and their Civic Outcomes; (2) CIRCLE Jointly Hosts…

  9. Using Literature Circles with English Language Learners at the Middle Level

    ERIC Educational Resources Information Center

    Farris, Pamela J.; Nelson, Pamela A.; L'Allier, Susan

    2007-01-01

    This article discusses literature circles and how to use them effectively with English Language Learners (ELLs) at the middle level. The focus of literature circles is to combine literacy skills and strategies in a supportive social atmosphere of a non-threatening peer group. All students need teacher modeling if literature circles are to work…

  10. Quality Circles: Implications for Training. Overview: ERIC Fact Sheet No. 24.

    ERIC Educational Resources Information Center

    Imel, Susan

    Quality circles are part of the movement to provide workers with increased autonomy, responsibility, and authority. Key elements of quality circles are the characteristics of their members, volunteer participation, regular meetings, training, problem identification, and solution implementation. The theoretical bases of quality circles include:…

  11. Problematizing Literature Circles as Forums for Discussion of Multicultural and Political Texts

    ERIC Educational Resources Information Center

    Thein, Amanda Haertling; Guise, Megan; Sloan, DeAnn Long

    2011-01-01

    In a six-week literature circle unit in a tenth-grade classroom, one group of students discussed Dorothy Allison's novel "Bastard out of Carolina." By criteria frequently used to judge the quality of discussion, this literature circle was successful. However, several key moments are highlighted that point to the limits of literature circles as…

  12. Native American Values and Management Education: Envisioning an Inclusive Virtuous Circle

    ERIC Educational Resources Information Center

    Verbos, Amy Klemm; Gladstone, Joe S.; Kennedy, Deanna M.

    2011-01-01

    Circles are symbols of interconnectedness. Behavioral circles can be vicious or virtuous. Many American Indians are caught in a vicious circle of exclusion from the purported benefits of Westernization, entrapment in its negative elements, and the ongoing undermining of their culture and thus their identities. Yet Native Americans, along with many…

  13. Culture Circles in adolescent empowerment for the prevention of violence

    PubMed Central

    Monteiro, Estela Maria Leite Meirelles; Neto, Waldemar Brandão; de Lima, Luciane Soares; de Aquino, Jael Maria; Gontijo, Daniela Tavares; Pereira, Beatriz Oliveira

    2015-01-01

    An action research based on Paulo Freire's Culture Circles was developed to implement a health education intervention involving adolescents, in collective knowledge construction about strategies for the prevention of violence. The data collection in the Culture Circles involved 11 adolescents and included observation and field diary, photographic records and recording. The educational action aroused a critical socio-political and cultural position in the adolescents towards the situations of vulnerability to violence, including the guarantee of human rights, justice and the combat of inequities; changes in the social relations, combat against discrimination and intolerance; expansion of access and reorientation of health services through intersectoral public policies. The intervention empowered the group of adolescents for the prevention of violence and permitted the inclusion of health professionals in the school context, from an interdisciplinary perspective, contributing to the establishment of social support and protection networks. PMID:25931647

  14. Rolling Circle Amplification of Complete Nematode Mitochondrial Genomes

    PubMed Central

    Tang, Sha; Hyman, Bradley C.

    2005-01-01

    To enable investigation of nematode mitochondrial DNA evolution, methodology has been developed to amplify intact nematode mitochondrial genomes in preparative yields using a rolling circle replication strategy. Successful reactions were generated from whole cell template DNA prepared by alkaline lysis of the rhabditid nematode Caenorhabditis elegans and a mermithid nematode, Thaumamermis cosgrovei. These taxa, representing the two major nematode classes Chromodorea and Enoplea, maintain mitochondrial genomes of 13.8 kb and 20.0 kb, respectively. Efficient amplifications were conducted on template DNA isolated from individual or pooled nematodes that were alive or stored at -80°C. Unexpectedly, these experiments revealed that multiple T. cosgrovei mitochondrial DNA haplotypes are maintained in our local population. Rolling circle amplification products can be used as templates for standard PCR reactions with specific primers that target mitochondrial genes or for direct DNA sequencing. PMID:19262866

  15. Algorithm of semicircular laser spot detection based on circle fitting

    NASA Astrophysics Data System (ADS)

    Wang, Zhengzhou; Xu, Ruihua; Hu, Bingliang

    2013-07-01

    In order to obtain the exact center of an asymmetrical and semicircular aperture laser spot, a method for laser spot detection method based on circle fitting was proposed in this paper, threshold of laser spot image was segmented by the method of gray morphology algorithm, rough edge of laser spot was detected in both vertical and horizontal direction, short arcs and isolated edge points were deleted by contour growing, the best circle contour was obtained by iterative fitting and the final standard round was fitted in the end. The experimental results show that the precision of the method is obviously better than the gravity model method being used in the traditional large laser automatic alignment system. The accuracy of the method to achieve asymmetrical and semicircular laser spot center meets the requirements of the system.

  16. Sampling great circles at their rate of innovation

    NASA Astrophysics Data System (ADS)

    Deslauriers-Gauthier, Samuel; Marziliano, Pina

    2013-09-01

    In this work, we show that great circles, the intersection of a plane through the origin and a sphere centered at the origin, can be perfectly recovered at their rate of innovation. Specifically, we show that 4K(8K - 7) + 7 samples are sufficient to perfectly recover K great circles, given an appropriate sampling scheme. Moreover, we argue that the number of samples can be reduced to 2K(4K - 1) while maintaining accurate results. This argument is supported by our numerical results. To improve the robustness to noise of our approach, we propose a modification that uses all the available information, instead of the critical amount. The increase in accuracy is demonstrated using numerical simulations.

  17. A multiloop generalization of the circle stability criterion

    NASA Technical Reports Server (NTRS)

    Safonov, M. G.; Athans, M.

    1979-01-01

    A frequency-domain stability criterion is presented, generalizing the well-known circle stability criterion to multiloop feedback systems having bounded nonlinearity, parameter variations, and/or frequency-dependent ignorance of component dynamics. Unlike previous generalizations, the theory is not restricted to weakly-coupled, diagonally dominant or nearly normal systems. Potential applications include the analysis of feedback system integrity and multiloop feedback system stability margins.

  18. BANQUET SPEECH Full Circle: Star Ferry to Stardust

    NASA Astrophysics Data System (ADS)

    Matthews, Clifford N.

    2008-10-01

    Good evening. I'd like to invite you to join me on a journey that could be entitled “Full Circle: Star Ferry to Stardust”. “Star Ferry” represents Hong Kong, my home town, and especially its university - Hong Kong University - as I knew it during the years of World War II. “Stardust” refers to our gathering here to report on our research on possible organic chemistry in space.

  19. SL(2, r) Yang-Mills Theory on a Circle

    NASA Astrophysics Data System (ADS)

    Bengtsson, Ingemar; Hallin, Joakim

    The kinematic of SL(2, ℝ) Yang-Mills theory on a circle is considered, for reasons that are spelt out. The gauge transformations exhibit hyperbolic fixed points, and this results in a physical configuration space with a non-Hausdorff “network” topology. The ambiguity encountered in canonical quantization is then much more pronounced than in the compact case and cannot be resolved through the kind of appeal made to group theory in that case.

  20. Rolling circle amplification detection of RNA and DNA

    DOEpatents

    Christian, Allen T.; Pattee, Melissa S.; Attix, Cristina M.; Tucker, James D.

    2004-08-31

    Rolling circle amplification (RCA) has been useful for detecting point mutations in isolated nucleic acids, but its application in cytological preparations has been problematic. By pretreating cells with a combination of restriction enzymes and exonucleases, we demonstrate RCA in solution and in situ to detect gene copy number and single base mutations. It can also detect and quantify transcribed RNA in individual cells, making it a versatile tool for cell-based assays.

  1. Micro-IBA analysis of Au/Si eutectic "crop-circles"

    NASA Astrophysics Data System (ADS)

    Amato, Giampiero; Battiato, Alfio; Croin, Luca; Jaksic, Milko; Siketic, Zdravko; Vignolo, Umberto; Vittone, Ettore

    2015-04-01

    When a thin gold layer is deposited onto the native oxide of a silicon wafer and is annealed at temperatures greater than 600 °C, peculiar circular features, few micrometers in diameter, with a regular polygon at the centre of each circle, reminiscent of so called "alien" crop circles, can be observed. A model has been recently proposed in Matthews et al. [1], where the formation of such circular structures is attributed to the interdiffusion of gold and silicon through holes in the native oxide induced by the weakening of the amorphous silica matrix occurring during the annealing process. The rupture of the liquid Au/Si eutectic disc surrounding the pinhole in the oxide causes the debris to be pulled to the edges of the disk, forming Au droplets around it and leaving an empty zone of bare silicon oxide. In this paper, we present a morphological study and a RBS/PIXE analyses of these circular structures, carried out by scanning electron microscopy and by 4 MeV C microbeam, respectively. The results confirm the depletion of gold in the denuded circular zones, and the presence of gold droplets in the centers, which can be attributed to the Au segregation occurring during the cooling stage.

  2. Of circles and spirals: bridging the gap between the leading circle and spiral wave concepts of cardiac reentry.

    PubMed

    Comtois, P; Kneller, J; Nattel, S

    2005-09-01

    The "leading circle model" was the first detailed attempt at understanding the mechanisms of functional reentry, and remains a widely-used notion in cardiac electrophysiology. The "spiral wave" concept was developed more recently as a result of modern theoretical analysis and is the basis for consideration of reentry mechanisms in present biophysical theory. The goal of this paper is to present these models in a way that is comprehensible to both the biophysical and electrophysiology communities, with the idea of helping clinical and experimental electrophysiologists to understand better the spiral wave concept and of helping biophysicists to understand why the leading circle concept is so attractive and widely used by electrophysiologists. To this end, the main properties of the leading circle and spiral wave models of reentry are presented. Their basic assumptions and determinants are discussed and the predictions of the two concepts with respect to pharmacological responses of arrhythmias are reviewed. A major difference between them lies in the predicted responses to Na(+)-channel blockade, for which the spiral wave paradigm appears more closely to correspond to the results of clinical and experimental observations. The basis of this difference is explored in the context of the fundamental properties of the models. PMID:16102499

  3. Microbial Biomass and Population Densities of Non-Sorted Circles in High Arctic Ecosystems

    NASA Astrophysics Data System (ADS)

    Rivera-Figueroa, F.; González, G.; Gould, W. A.; Cantrell, S.; Pérez, J.

    2006-12-01

    Non-sorted circles are small patterned-ground features that occur in arctic soils as a result of intensive frost heave action. This tundra feature has been extensively described. However, little is known about the ecological relationships between this pattern and above- and belowground organisms. In this study, we compare the biomass and populaton densities of microbes in non-sorted circles and the vegetated surrounding soils (inter-circles) in the High Arctic. We collected soil samples during the summer of 2004 and 2005 on Banks and Prince Patrick and Ellef Ringnes Islands, Canada. Soil samples (0-10 cm) were gathered from non- sorted circles and inter-circles along a topographic sequence: dry (ridge), mesic (mid slope) and wet (valley) and along three transects in zonal (mesic) sites on each island. We estimated total microbial biomass and bacterial population densities using substrate induce respiration (SIR) and the most probable number method (MPN), respectively. We also isolated soil fungi using Rose Bengal and Saboraud Dextrose culture media. We are in the process of analyzing the catena samples using a terminal restriction fragment length polymorphism (TRFLP) technique of PCR-amplified 16S rRNA. Based on the SIR trials, the average microbial biomass at the mid slope position in the Banks site (Green Cabin) was 0.49 mg C g-1 dry soil in the non- sorted circles and 0.95 mg C g-1 dry soil in the inter-circles. At Prince Patrick Island (Mould Bay) the microbial biomass was 0.54 mg C g-1 dry soil in the non-sorted circles and 0.74 mg C g-1 dry soil in the inter-circles. In Ellef Ringnes (Isachsen) the microbial biomass was 0.09 mg C g-1 dry soil in the non- sorted circles and 0.14 mg C g-1 dry soil in the inter-circles. At the mesic site at Green Cabin, bacteria vary from 2.92 x 106 cell g-1 dry soil in the non-sorted circles to 6.74 x 106 cell g-1 dry soil in the inter-circles. At Mould Bay the range was 7.67 x 105 cells g-1 dry soil in the non-sorted circles

  4. Can the Expanding Circle Own English? Comments on Yoo's "Nonnative Teachers in the Expanding Circle and the Ownership of English"

    ERIC Educational Resources Information Center

    Ren, Wei

    2014-01-01

    Yoo's (2014) article raises a number of questions concerning local teachers' status and the ownership of English in the Expanding Circle. In this article, I address five issues that I see as most important relating to the ownership of English and empowering local teachers in the Expanding Circle. I provide up-to-date evidence of World…

  5. Detecting miRNA by producing RNA: a sensitive assay that combines rolling-circle DNA polymerization and rolling circle transcription.

    PubMed

    Li, Xuemei; Zheng, Fuwei; Ren, Rui

    2015-08-01

    Target miRNA was detected by producing RNA: rolling circle polymerization (RCP) and rolling circle transcription (RCT) were interlinked to provide dual amplification, producing multiplied malachite green (MG) aptamers, and a signal was generated by the SERS (surface-enhanced Raman scattering) quantification of the MG molecules that were bound to the transcripts. PMID:26120604

  6. HaloTag mediated artificial cellulosome assembly on a rolling circle amplification DNA template for efficient cellulose hydrolysis.

    PubMed

    Sun, Qing; Chen, Wilfred

    2016-05-10

    We report here the generation of four-component artificial cellulosomes onto a DNA scaffold using the self-labeling HaloTag for DNA conjugation. The resulting structures exhibited significantly improved cellulosome assembly as well as cellulose hydrolysis over compatible structures generated using protein scaffolds. Cellulose hydrolysis was further enhanced by 2-fold using the more complex cellulosome structures assembled onto DNA templates generated by rolling circle amplification (RCA). The flexibility to insert additional hybridization sites in a multiplexing manner using RCA should enable the assembly of a larger array of cellulases to better mimic the enzyme diversity of naturally occurring cellulosomes. PMID:27117678

  7. Polarization-Independent, Thin, Broadband Metamaterial Absorber Using Double-Circle Rings Loaded with Lumped Resistances

    NASA Astrophysics Data System (ADS)

    Chen, Junfeng; Huang, Xiutao; Zerihun, Gebru; Hu, Zhaoyang; Wang, Shengming; Wang, Guodong; Hu, Xiwei; Liu, Minghai

    2015-11-01

    We present a broadband and polarization-insensitive metamaterial absorber (MA) composed of a dielectric substrate sandwiched with double-circle rings (DCRs) and welded with lumped resistances and continuous metal film. The structure is designed with thickness of 3 mm and investigated by simulation, fabrication, and experiment. The results show that the composite MA loaded with lumped resistances has wider absorptivity compared with a structure with only DCRs. The simulation results indicate that the proposed absorber achieves 7.60-GHz-wide absorption from 8.87 GHz to 16.47 GHz with absorptivity greater than 90%, in excellent agreement with experimental results. Further simulations indicate that there exist optimal values for the lumped resistances for which the absorptivity is the highest and the bandwidth widest. Additionally, the proposed MA is polarization insensitive at normal incidence. Simulation results for wide angles of incidence of both transverse electric and transverse magnetic waves are also investigated.

  8. Stereoscopic Machine-Vision System Using Projected Circles

    NASA Technical Reports Server (NTRS)

    Mackey, Jeffrey R.

    2010-01-01

    A machine-vision system capable of detecting obstacles large enough to damage or trap a robotic vehicle is undergoing development. The system includes (1) a pattern generator that projects concentric circles of laser light forward onto the terrain, (2) a stereoscopic pair of cameras that are aimed forward to acquire images of the circles, (3) a frame grabber and digitizer for acquiring image data from the cameras, and (4) a single-board computer that processes the data. The system is being developed as a prototype of machine- vision systems to enable robotic vehicles ( rovers ) on remote planets to avoid craters, large rocks, and other terrain features that could capture or damage the vehicles. Potential terrestrial applications of systems like this one could include terrain mapping, collision avoidance, navigation of robotic vehicles, mining, and robotic rescue. This system is based partly on the same principles as those of a prior stereoscopic machine-vision system in which the cameras acquire images of a single stripe of laser light that is swept forward across the terrain. However, this system is designed to afford improvements over some of the undesirable features of the prior system, including the need for a pan-and-tilt mechanism to aim the laser to generate the swept stripe, ambiguities in interpretation of the single-stripe image, the time needed to sweep the stripe across the terrain and process the data from many images acquired during that time, and difficulty of calibration because of the narrowness of the stripe. In this system, the pattern generator does not contain any moving parts and need not be mounted on a pan-and-tilt mechanism: the pattern of concentric circles is projected steadily in the forward direction. The system calibrates itself by use of data acquired during projection of the concentric-circle pattern onto a known target representing flat ground. The calibration- target image data are stored in the computer memory for use as a

  9. Circles on pommel horse with a suspended aid: spatio-temporal characteristics.

    PubMed

    Fujihara, Toshiyuki; Gervais, Pierre

    2012-01-01

    A suspended aid is popular for learning circles and for refining circle technique on pommel horse. The aim of this study was to investigate the effect of using a suspended aid on the biomechanical characteristics of circles. This first study focused specifically on the spatio-temporal characteristics of circles. Eighteen gymnasts performed three sets of 10 circles with and without a suspended aid on a pommel horse under which two force plates were set. Three-dimensional coordinates were acquired using 13 Qualisys motion tracking cameras operating at 100 Hz. The results showed that circles with the aid were characterised by a smaller body flexion angle, a greater shoulder angle, a greater ankle circle diameter, earlier hand releases, and a longer total duration. In contrast, the body lateral flexion angle, the arm-leaning angle, and the shoulder circle diameter remained relatively similar to circles without the aid. It was confirmed that circles with the aid actually appeared to be more desirable in terms of the movement amplitude. In this sense, a suspended aid could function as spotting, which is often used for a progression to learn gymnastics skills and to let gymnasts experience a desired movement pattern. PMID:22313144

  10. The Risks We Dread: A Social Circle Account

    PubMed Central

    Galesic, Mirta; Garcia-Retamero, Rocio

    2012-01-01

    What makes some risks dreadful? We propose that people are particularly sensitive to threats that could kill the number of people that is similar to the size of a typical human social circle. Although there is some variability in reported sizes of social circles, active contact rarely seems to be maintained with more than about 100 people. The loss of this immediate social group may have had survival consequences in the past and still causes great distress to people today. Therefore we hypothesize that risks that threaten a much larger number of people (e.g., 1000) will not be dreaded more than those that threaten to kill “only” the number of people typical for social circles. We found support for this hypothesis in 9 experiments using different risk scenarios, measurements of fear, and samples from different countries. Fear of risks killing 100 people was higher than fear of risks killing 10 people, but there was no difference in fear of risks killing 100 or 1000 people (Experiments 1–4, 7–9). Also in support of the hypothesis, the median number of deaths that would cause maximum level of fear was 100 (Experiments 5 and 6). These results are not a consequence of lack of differentiation between the numbers 100 and 1000 (Experiments 7 and 8), and are different from the phenomenon of “psychophysical numbing” that occurs in the context of altruistic behavior towards members of other communities rather than in the context of threat to one's own community (Experiment 9). We discuss several possible explanations of these findings. Our results stress the importance of considering social environments when studying people's understanding of and reactions to risks. PMID:22509250

  11. 3-D Reservoir and Stochastic Fracture Network Modeling for Enhanced Oil Recovery, Circle Ridge Phosphoria/Tensleep Reservoir, and River Reservation, Arapaho and Shoshone Tribes, Wyoming

    SciTech Connect

    La Pointe, Paul R.; Hermanson, Jan

    2002-09-09

    The goal of this project is to improve the recovery of oil from the Circle Ridge Oilfield, located on the Wind River Reservation in Wyoming, through an innovative integration of matrix characterization, structural reconstruction, and the characterization of the fracturing in the reservoir through the use of discrete fracture network models.

  12. Stieltjes-type polynomials on the unit circle

    NASA Astrophysics Data System (ADS)

    de La Calle Ysern, B.; Lagomasino, G. Lopez; Reichel, L.

    2009-06-01

    Stieltjes-type polynomials corresponding to measures supported on the unit circle mathbb{T} are introduced and their asymptotic properties away from mathbb{T} are studied for general classes of measures. As an application, we prove the convergence of an associated sequence of interpolating rational functions to the corresponding Caratheodory function. In turn, this is used to give an estimate of the rate of convergence of certain quadrature formulae that resemble the Gauss-Kronrod rule, provided that the integrand is analytic in a neighborhood of mathbb{T} .

  13. From spherical circle coverings to the roundest polyhedra

    NASA Astrophysics Data System (ADS)

    Tarnai, T.; Gáspár, Z.; Lengyel, A.

    2013-11-01

    The problem treated here is: amongst the convex polyhedra that can be circumscribed about the unit sphere and have ? faces, which has the minimum surface area? A new optimization method based on mechanical analogies is worked out to solve this problem. By using this method, new computer-generated solutions are presented for ? and ?. The second of these two conjectured roundest polyhedra has icosahedral symmetry. The relation of the results of this problem to the minimum coverings of the sphere with equal circles is discussed.

  14. Social Circles: A 3D User Interface for Facebook

    NASA Astrophysics Data System (ADS)

    Rodrigues, Diego; Oakley, Ian

    Online social network services are increasingly popular web applications which display large amounts of rich multimedia content: contacts, status updates, photos and event information. Arguing that this quantity of information overwhelms conventional user interfaces, this paper presents Social Circles, a rich interactive visualization designed to support real world users of social network services in everyday tasks such as keeping up with friends and organizing their network. It achieves this by using 3D UIs, fluid animations and a spatial metaphor to enable direct manipulation of a social network.

  15. The Phenomenological Circle and the Unity of Life and Thought.

    PubMed

    Atwood, George E; Stolorow, Robert D

    2016-06-01

    This paper describes the important role of our deep immersions in philosophy in the development of our phenomenological-contextualist approach to psychoanalysis. Influenced most particularly by the phenomenological movement, our collaborative dialogue over more than four decades has led us to a shared commitment to reflection upon the philosophical underpinnings and constitutive contexts of origin of all our theoretical ideas. The growth of our thinking follows an endlessly recurring phenomenological circle joining theoretical perspectives with the inquirers from whose emotional worlds they arise. PMID:27248037

  16. Circle of least confusion of a spherical reflector.

    PubMed

    Hosken, Robert W

    2007-06-01

    A simple, tractable equation is provided for determining the size and location of the circle of least confusion of a concave spherical reflector. This method is exact for the object at infinity and with wave effects neglected. Designers of large radius Arecibo-like telescopes, both radio and optical, with symmetrical, spherical primaries should find the method useful. The mathematical results are valid for apertures with an angle of incidence up to 45 degrees. Comparisons of the location of the disk of least confusion with longitudinal spherical aberration and the radius of the disk with transverse spherical aberration are presented. PMID:17514263

  17. Circle of Willis Configuration as a Determinant of Intracranial Dolichoectasia

    PubMed Central

    Gutierrez, Jose; Sultan, Sally; Bagci, Ahmet; Rundek, Tatjana; Alperin, Noam; Elkind, Mitchell S.V.; Sacco, Ralph L.; Wright, Clinton B.

    2015-01-01

    Background Circle of Willis (COW) variants might influence arterial caliber in the brain. We hypothesized that these variants would be associated with the prevalence of intracranial dolichoectasia (DE). Methods We examined COW variants and DE in a sample of stroke-free participants (n = 436) undergoing magnetic resonance angiography (MRA) as part of a population-based study. Large intracranial arterial diameters were obtained when available; if not, the artery was defined as hypoplastic or absent according to its visibility on MRA. Subscores for the anterior and the posterior circulations were created. DE was defined as arterial diameters ≥ 2 SD above the population mean for that artery, adjusting for intracranial volume. Generalized linear models with a Poisson distribution were used to evaluate predictors of both absent and hypoplastic vessels, and logistic regression was used to assess the odds ratio (OR) and 95% confidence interval (95% CI) of DE depending on COW variants. Results Only 44% of the sample had all 14 arteries present, 32% lacked 1 artery, 18% lacked 2 and 6% lacked 3 or more. DE of at least 1 artery was not associated with the total number of hypoplastic or absent arteries, but DE in a posterior circulation artery was weakly associated with the number of absent arteries in the posterior circulation (β coefficient = 0.36, p = 0.06). DE of at least 1 artery was more frequent in those with 1 or more absent arteries (OR 1.27, 95% CI 1.03–1.57). Posterior circulation DE was more frequent in participants with at least 1 or more absent arteries at any location (OR 1.35, 95% CI 1.02–1.78). Participants with an incomplete posterior COW were more likely to have DE in the anterior circulation (OR 1.52, 95% CI 1.01–2.33). Having an absent left anterior cerebral artery (ACA) A1 segment was associated with right ACA DE (OR 34.1, 95% CI 3.16–368.2); an absent right ACA was associated with left ACA DE (OR 14.1, 95% CI 1.69–118.28). Absence of 1 (OR 1

  18. Spectra of mothers of premature children about the educative circle of culture.

    PubMed

    Couto, Camila Santos do; Tupinambá, Milena Colares; Rangel, Aldecira Uchôa Monteiro; Frota, Mirna Albuquerque; Martins, Elis Mayre da Costa Silveira; Nobre, Caroline Soares; Landim, Átima Luna Pinheiro

    2014-12-01

    We sought to know the spectra of mothers of premature children regarding their experience with circle of culture of educational character and identifying the learning provided by the circle of culture about newborn care after hospital discharge. A descriptive study was performed in a hospital located in Fortaleza, Brazil. Three meetings of a circle of culture with 17 mothers of premature newborns were performed. The interpretation of the corpus was performed using thematic analysis. Emerged from the categories: Maternal experience in a circle of culture; Promoted social support among mothers through the circle of culture; and Learning provided by the circle of culture. It was concluded that teaching parents during the hospitalization of the child should be held in a way to involve parents in the care of the newborn, provide moments of health education, opportunities for support and dialogue between professionals and family. PMID:25830729

  19. Participant Experiences of Talking Circles on Type 2 Diabetes in Two Northern Plains American Indian Tribes

    PubMed Central

    Struthers, Roxanne; Hodge, Felicia Schanche; Geishirt-Cantrell, Betty; De Cora, Lorelei

    2011-01-01

    The Talking Circle, a culturally appropriate, 12-week educational intervention, was employed on two Northern Plains American Indian reservations to provide information on type 2 diabetes. In a phenomenological study, funded as a minority supplement to the Talking Circle intervention, the authors asked 8 American Indian participants of the Talking Circle to describe their experience of being an American Indian Talking Circle participant. Seven common themes describe the phenomenon of participating in a Talking Circle diabetic intervention. The Talking Circle technique was effective in providing information on type 2 diabetes through culturally appropriate community sharing. Type 2 diabetes is viewed by both outsiders and those involved as a chronic disease of the utmost concern in American Indian communities. PMID:14556421

  20. Maintenance of the 2 microns circle plasmid in populations of Saccharomyces cerevisiae.

    PubMed Central

    Futcher, A B; Cox, B S

    1983-01-01

    The 2 microns circle plasmid is maintained at high frequencies in populations of yeast cells. To find out how the plasmid is maintained, three forces were measured: the selective advantage or disadvantage conferred by 2 microns circles, the rate of generation of [Cir0] cells, and the rate of illegitimate transfer of 2 microns circles from cell to cell. It was found that under the conditions used, 2 microns circles confer a selective disadvantage of about 1%, that [Cir0] cells are generated at the rate of 7.6 x 10(-5) per [Cir+] cell per generation, and that illegitimate transfer of 2 microns circles occurs at a rate less than 10(-7) per recipient cell per generation. The most likely explanation of 2 microns circle maintenance is that the plasmid is sexually transmitted at such a rate that it spreads through populations despite selection against it. Images PMID:6341357

  1. Eccentricity on AN Image Caused by Projection of a Circle and a Sphere

    NASA Astrophysics Data System (ADS)

    Matsuoka, R.; Maruyama, S.

    2016-06-01

    Circular targets on a plane are often utilized in photogrammetry, particularly in close range photogrammetry, while spherical targets are sometimes utilized in industrial applications. Both a circle and a sphere are projected as an ellipse onto an image. There is an eccentricity on an image between the centre of the projected ellipse and the projected location of the centre of a circle or a sphere. Since only the centre of the projected ellipse is measured, the correction of the eccentricity is considered to be necessary for highly accurate measurement. This paper shows a process to derive general formulae to calculate an eccentricity of a circle and a sphere using the size and the location of a circle or a sphere, and the focal length, the position and the attitude of a camera. Furthermore the paper shows methods to estimate the eccentricity of a circle and a sphere from the equation of the projected ellipse of a circle or a sphere on an image.

  2. Perturbing polynomials with all their roots on the unit circle

    NASA Astrophysics Data System (ADS)

    Mossinghoff, M. J.; Pinner, C. G.; Vaaler, J. D.

    1998-10-01

    Given a monic real polynomial with all its roots on the unit circle, we ask to what extent one can perturb its middle coefficient and still have a polynomial with all its roots on the unit circle. We show that the set of possible perturbations forms a closed interval of length at most 4, with 4 achieved only for polynomials of the form x(2n) + cx(n) + 1 with c in [-2, 2]. The problem can also be formulated in terms of perturbing the constant coefficient of a polynomial having all its roots in [-1, 1]. If we restrict to integer coefficients, then the polynomials in question are products of cyclotomics. We show that in this case there are no perturbations of length 3 that do not arise from a perturbation of length 4. We also investigate the connection between slightly perturbed products of cyclotomic polynomials and polynomials with small Mahler measure. We describe an algorithm for searching for polynomials with small Mahler measure by perturbing the middle coefficients of products of cyclotomic polynomials. We show that the complexity of this algorithm is O(C-root d), where d is the degree, and we report on the polynomials found by this algorithm through degree 64.

  3. Circles with a suspended aid: reducing pommel reaction forces.

    PubMed

    Fujihara, Toshiyuki; Gervais, Pierre

    2012-03-01

    The aim of this study was to investigate the influence of a suspended aid on the reaction forces during a basic skill on pommel horse. Twenty gymnasts performed three sets of 10 circles with and without a suspended aid on a pommel horse under which two force plates were set. The results confirmed that the suspended aid could reduce the magnitude of the pommel reaction forces during circles while maintaining the general loading pattern. On the left hand, the average and peak forces were attenuated to 0.59 body weight (BW) and 0.85 BW from 0.76 BW and 1.13 BW, respectively. The right hand experienced slightly larger forces with no-aid trials, but the asymmetry between the hands decreased with the aid. Despite a relatively large variability, all gymnasts experienced smaller impact peak forces with the aid. A suspended aid is most commonly used for a beginner gymnast as an introduction to pommel horse exercises. However, this study confirmed that it can also be useful for all levels of gymnasts who would like to practice pommel horse exercises with reduced pommel reaction forces for a purpose such as a progression for learning a new skill, control of training volume, or rehabilitation. PMID:22518943

  4. A grounded theory of female adolescents' dating experiences and factors influencing safety: the dynamics of the Circle

    PubMed Central

    Toscano, Sharyl E

    2007-01-01

    Background This paper describes the nature and characteristics of the dating relationships of adolescent females, including any of their experiences of abuse. Methods A grounded theory approach was used with 22 theoretically sampled female adolescents ages 15–18. Results Several important themes emerged: Seven stages of dating consistently described the relationships of female adolescents. A circle consisting of two interacting same sex peer groups provided structure for each teen as they navigated the dating course. The circle was the central factor affecting a female adolescent's potential for risk or harm in dating relationships. Teens defined abuse as an act where the intention is to hurt. Having once succumbed to sexual pressure, teens felt unable to refuse sex in subsequent situations. Conclusion An awareness of both the stages of dating and the dynamics of the circle will assist health care providers to plan and implement interventions in the female adolescent population. Study findings on factors and influences that support non-abusive versus abusive relationship might help identify female teens at risk and/or support interventions aimed at preventing dating violence. PMID:17883833

  5. Mitochondrial plasmids of sugar beet amplified via rolling circle method detected during curtovirus screening.

    PubMed

    Homs, Maria; Kober, Sigrid; Kepp, Gabi; Jeske, Holger

    2008-09-01

    Crops of sugar beet have been considerably impaired by infection with Beet curly top virus (BCTV) during the past decades. Quick and reliable diagnostic techniques are therefore desirable to detect this circular single-stranded DNA-containing geminivirus. Techniques combining either tissue printing or blot hybridization, or rolling circle amplification (RCA) and restriction fragment length polymorphism (RFLP) were compared. Although they easily detected BCTV with certainty, both exhibited apparent false positive results which have been scrutinized in closer detail. Uninfected control plants revealed unspecific signals due to probe attachment on tissue blots, and dominant fragment patterns upon RCA/RFLP which did not hybridize with BCTV-specific probes. Cloning and sequencing of these DNA fragments showed that they were amplified from mitochondrial plasmids. Examination of their genome structure revealed no relationship with geminiviruses or their satellites. PMID:18562034

  6. Proposal for high-birefringent terahertz photonic crystal fiber with all circle air holes

    NASA Astrophysics Data System (ADS)

    Wu, Zhiqing; Zhou, Xiaoyan; Shi, Zhaohua; Xia, Handing; Huang, Jin; Jiang, Xiaodong; Wu, Weidong

    2016-03-01

    A type of high-birefringent terahertz (THz) photonic crystal fiber (PCF) with all circle air holes is proposed. The characteristics including birefringence, dispersion, and confinement loss are numerically analyzed in detail by using the finite element methods. Simulation results show that the proposed THz PCFs exhibit high birefringence on the level of 10-2 in the frequency range of 2 to 4 THz, which is realized by the minor position adjustment of air holes in the first ring of the cladding. We believe that the proposed THz PCFs can be fabricated without complications due to their simple structure. In addition, two porous-core THz PCFs are proposed and the birefringence property is investigated.

  7. Periodic fluorescent silver clusters assembled by rolling circle amplification and their sensor application.

    PubMed

    Ye, Tai; Chen, Jinyang; Liu, Yufei; Ji, Xinghu; Zhou, Guohua; He, Zhike

    2014-09-24

    A simple method for preparing DNA-stabilized Ag nanoclusters (NCs) nanowires is presented. To fabricate the Ag NCs nanowires, we use just two unmodified component strands and a long enzymatically produced scaffold. These nanowires form at room temperature and have periodic sequence units that are available for fluorescence Ag NCs assembled which formed three-way junction (TWJ) structure. These Ag NCs nanowires can be clearly visualized by confocal microscopy. Furthermore, due to the high efficiency of rolling circle amplification reaction in signal amplification, the nanowires exhibit high sensitivity for the specific DNA detection with a wide linear range from 6 to 300 pM and a low detection limit of 0.84 pM, which shows good performance in the complex serum samples. Therefore, these Ag NCs nanowires might have great potential in clinical and imaging applications in the future. PMID:25116051

  8. Design and Application of Rolling Circle Amplification for a Tumor-Specific Drug Carrier.

    PubMed

    Kim, Jong Hwan; Jang, Mihue; Kim, Young-Je; Ahn, Hyung Jun

    2015-10-01

    It is challenging to design rolling circle amplification (RCA) for tumor-selective delivery of drugs. Here, we devise a doxorubicin nanocarrier composed of RCA products, cholesterol-DNA, and folate-DNA conjugates. RCA products, designed to contain tandem repeats of short hairpin DNA, employ the repeated sequences complementary to both DNA conjugates, and thus RCA products/cholesterol-DNA/folate-DNA complexes, generated via sequential base pairing processes, acquire the amphiphilic properties that facilitate self-assembly into the highly condensed nanoparticles (RCA nanoparticles). Doxorubicin-loaded RCA nanoparticles, especially with high cargo capacity, release drugs to the environment with the aid of acidity and show selective cytotoxicity to cancer cells. Particularly, the condensed structures enable RCA nanoparticles to be resistant to nucleases in the blood. These results show that RCA nanoparticles have great potential as a doxorubicin carrier for targeted cancer therapy, and furthermore, our strategy provides an alternative tool to exploit RCA techniques on drug delivery systems. PMID:26361253

  9. Air tightness of buildings in the Arctic Circle housing fair, Rovaniemi, Finland

    NASA Astrophysics Data System (ADS)

    Ryynanen, Kai

    2001-03-01

    Air leak through the external envelope leads to many inconveniences. Higher consumption of heating energy, draft and possible moisture defects are the result of air infiltration. The automatic ventilation system of the house can also be thrown off balance. The factors mentioned above, together with poor knowledge of airtightness of houses, was reason to start this project airtightness of the buildings in the arctic circle housing fair in Rovaniemi, Finland. The airtightness of houses measured by using the fan pressurization method, according to international standard ISO DIS 9972. The fan pressurization method means that in building caused negative air-pressure from normal approximately 0 Pa up to 50 Pa over the buildings envelope. The air leakage points are searched by using thermal camera. In this project made research differences between materials, structures and production styles. The method and equipment for measuring airtightness are tested and developed in project.

  10. Coordinated circling behavior of Daphnia swarming around an optical marker

    NASA Astrophysics Data System (ADS)

    Ordemann, Anke; Russell, David F.; Moss, Frank

    2002-03-01

    The common fresh water zooplankton Daphnia, as well as many other zooplankton species, are known to form swarms as a predator confusing behavior. In rare events in the field as well as in laboratory environments a swarm of Daphnia has been observed to perform a vortex like motion, similar to a flock of birds circling before coming to rest. To shed more light on this coordinated behavior we study experimentally the motion of Daphnia inside a swarm in respect to the motion of single Daphnia. Daphnia can be induced to swarm by an optical marker such as a vertical shaft of light in the visual range, to which they are attracted. Following the tracks of several Daphnia and characterizing their paths by a variety of measures we observe the development of a circular motion around the optical marker.

  11. Laser with injected signal: perturbation of an invariant circle

    NASA Astrophysics Data System (ADS)

    Solari, Hernán G.; Oppo, Gian-Luca

    1994-09-01

    We study the locked-unloked transition for a class of lasers with injected signal. The transition is produced by a parametric breaking of the invariant circle that represents the free running laser. A Hopf-saddle-node codimension two bifurcation coupled with a phase-drift re-injection mechanism organizes the flow. Fixed points (locked states), periodic orbits and tori, T2, of two inequivalent types as well as hetero-homoclinic loops are found by using methods of bifurcation theory and are illustrated with computer simulations. We discuss the dependence of the flow patterns with respect to the laser parameters and, in particular, we show that the detuning between atomic and cavity frequencies plays a fundamental role for the dynamics.

  12. G2 cubic transition between two circles with shape control

    NASA Astrophysics Data System (ADS)

    Habib, Zulfiqar; Sakai, Manabu

    2009-01-01

    This paper describes a method for joining two circles with an S-shaped or with a broken back C-shaped transition curve, composed of at most two spiral segments. In highway and railway route design or car-like robot path planning, it is often desirable to have such a transition. It is shown that a single cubic curve can be used for blending or for a transition curve preserving G2 continuity with local shape control parameter and more flexible constraints. Provision of the shape parameter and flexibility provide freedom to modify the shape in a stable manner which is an advantage over previous work by Meek, Walton, Sakai and Habib.

  13. Literature circles book club for science and language arts

    NASA Astrophysics Data System (ADS)

    Bombard, Britain

    Students from an urban middle school participated in a Science Book Club for one semester using the literature circles format. These students voluntarily attended twice weekly lunch meetings, reading books that followed their Grade 7 science classes. Groups of three to six participants read the same text, each performing rotating jobs to improve group discussions during meetings. When a group completed a book, participants created a presentation to share what they learned with the other groups in the club and the researcher/teacher. This research measured gains in science content knowledge and language arts skills focusing on reading comprehension, and literary response and analysis. Gains were measured using pre-existing district benchmarks. An ANCOVA showed that while no gains were found in science content knowledge, there were gains in language arts in the areas of reading comprehension and literary response and analysis.

  14. Electron Cyclotron Emission Imaging on ITER with Rowland Circle Optics

    NASA Astrophysics Data System (ADS)

    Liu, Jason; Lee, Woochang; Leem, June-Eok; Bitter, Manfred; Park, Hyeon; Yun, Gunsu

    2015-11-01

    The implementation of advanced electron cyclotron emission imaging (ECEI) systems on the major tokamaks TEXTOR1, DIII-D2,3, KSTAR4, EAST5, and ASDEX Upgrade6 has revolutionized the diagnosis of MHD activities and improved our understanding of various instabilities. However, the conventional ECEI systems cannot be applied to ITER because of the space constraints and excessive radiation that would be encountered in the diagnostic port plugs. This paper describes an alternative optical concept that employs the Rowland circle imaging geometry to implement an advanced ECEI system on ITER that is suitable for the tight space and harsh environments of the diagnostic port plugs. Such a system would match the capabilities of conventional ECEI diagnostics and would be capable of simultaneous core and edge measurements.

  15. Seeds of Change: Using Peacemaking Circles to Build a Village for Every Child

    ERIC Educational Resources Information Center

    Boyes-Watson, Carolyn

    2005-01-01

    Roca, Inc., a grassroots human development and community organization, has adopted the peacemaking circle as a tool in its relationship building with youth, communities, and formal systems. Circles are a method of communication derived from aboriginal and native traditions. In Massachusetts, the Department of Social Services and the Department of…

  16. Implementing the patient circle. Call on patients to help improve perceptions of health care quality.

    PubMed

    Ostasiewski, P; Fugate, D L

    1994-01-01

    Adapting the quality-circle concept to a health care setting helped one hospital solve a problem and boosted its image among patients. The "patient circle" technique is one step health care providers can take toward delivering "total customer value," a quality perception that can mean the difference between surviving and thriving in the future. PMID:10154633

  17. Health Literacy Study Circles[superscript +]. Introduction: Overview, Planning, and Facilitation Tips

    ERIC Educational Resources Information Center

    Rudd, Rima; Soricone, Lisa; Santos, Maricel; Zobel, Emily; Smith, Janet

    2005-01-01

    A Health Literacy Study Circle[superscript +] is a multi-session professional development activity for adult education practitioners, conducted by a facilitator. All the information and materials required to conduct each Health Literacy Study Circle[superscript +] is presented in two parts: this Introduction and the "Facilitator's Guide" for each…

  18. "Ownership" of English in the Outer Circle: An Alternative to the NS-NNS Dichotomy

    ERIC Educational Resources Information Center

    Higgins, Christina

    2003-01-01

    The linguistic classification of English speakers from outer-circle countries, such as India, Malaysia, and Singapore, is often ambiguous because the Englishes they speak are considered different from interlanguages yet are not considered native varieties. This study investigates whether outer-circle speakers can be viewed as equivalent to…

  19. Literature Circles: A Tool for Self-Determination in One Middle School Inclusive Classroom.

    ERIC Educational Resources Information Center

    Blum, H. Timothy; Lipsett, Laura R.; Yocom, Dorothy Jean

    2002-01-01

    Fourteen students in a multiage middle school inclusive classroom engaged in literature circles while reading various short stories and novels during the course of one school semester. Students with special needs (n=7) believed literature circles helped them read, analyze, and discuss literature selections. They also showed gains in…

  20. Three Keys for Successful Circle Time: Responding to Children with Diverse Abilities.

    ERIC Educational Resources Information Center

    Wald, Penelope J.; And Others

    This article presents strategies that promote responsive instruction of young children with diverse abilities during teacher-directed large group times, specifically "circle time." It uses a traditional circle time format to show how such typical activities as observing the weather can be modified to provide multisensory, multilevel, and multiple…

  1. Quality Circles in the Classroom: An Experiment in the Pedagogical Uses of Japanese Management Methods.

    ERIC Educational Resources Information Center

    Hirshfield, Claire

    An on-going experiment in the classroom use of the Japanese quality circle concept of consensus and group management has been conducted for the past 2 years at the Ogontz Campus of Pennsylvania State University. Quality circles composed of the teacher and eight student volunteers meet weekly for 45 minutes, with each member informing three other…

  2. Planning Community-Wide Study Circle Programs. A Step-by-Step Guide.

    ERIC Educational Resources Information Center

    McCoy, Martha; And Others

    This guide contains ideas and documents from study circle programs throughout the United States. The guide is organized in five parts that cover the following topics: (1) introduction--what are study circles, how do they function?; (2) basic steps in creating a community-wide program; (3) sample documents including program description, community…

  3. An Action Research Study Involving Motivating Middle School Students' Learning through Online Literature Circles

    ERIC Educational Resources Information Center

    Falter Thomas, Angela

    2014-01-01

    In this study, I explored the motivation of middle school students participating in online literature circles facilitated by college students, compared to traditional face-to-face literature circles they previously utilized. Sixty-eight rural, middle school students from two English teachers' classrooms took part in two sets of online literature…

  4. Circle Time: An Exploratory Study of Activities and Challenging Behavior in Head Start Classrooms

    ERIC Educational Resources Information Center

    Zaghlawan, Hasan Y.; Ostrosky, Michaelene M.

    2011-01-01

    The purpose of this descriptive study was to examine circle time activities in eight Head Start classrooms. A total of 7 h of observations occurred in eight classrooms. Songs and academic activities were the most frequently occurring activities. Challenging behavior during circle time also was examined. The three activities with the highest…

  5. Toward a "Lifetime of Literacies": Library Reading Circles for College Students

    ERIC Educational Resources Information Center

    Howrey, Mary M.; Rachelson, Esther S.

    2009-01-01

    This qualitative case study of the ReadDeVry reading circles program, a DeVry University funded project, identifies the theoretical and practical considerations for reading circles programs serving college students. As designed, the program addresses a number of the issues raised recently by national organizations such as the American College…

  6. When Two Circles Determine a Triangle. Discovering and Proving a Geometrical Condition in a Computer Environment

    ERIC Educational Resources Information Center

    Metaxas, Nikolaos; Karagiannidou, Andromachi

    2010-01-01

    Visualization of mathematical relationships enables students to formulate conjectures as well as to search for mathematical arguments to support these conjectures. In this project students are asked to discover the sufficient and necessary condition so that two circles form the circumscribed and inscribed circle of a triangle and investigate how…

  7. A Historical Note on the Proof of the Area of a Circle

    ERIC Educational Resources Information Center

    Wilamowsky, Yonah; Epstein, Sheldon; Dickman, Bernard

    2011-01-01

    Proofs that the area of a circle is nr[superscript 2] can be found in mathematical literature dating as far back as the time of the Greeks. The early proofs, e.g. Archimedes, involved dividing the circle into wedges and then fitting the wedges together in a way to approximate a rectangle. Later more sophisticated proofs relied on arguments…

  8. Employer-employee based quality circles in Japan: human resource policy implications for American firms.

    PubMed

    Munchus, G

    1983-04-01

    This paper traces the development of the quality circle in Japan with reference to such traditions as permanent employment, nenko (seniority-based compensation), enterprise unionism, and management paternalism. Quality circles are examined as tools for motivating employees, reducing labor turnover, effecting employee "career expansion," and allowing employee participation in job redesign. PMID:10263059

  9. VIEW FROM EAST SIDE OF ELM DRIVE/BIRCH CIRCLE BLOCK, SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW FROM EAST SIDE OF ELM DRIVE/BIRCH CIRCLE BLOCK, SHOWING SLOPING TOPOGRAPHY. VIEW FACING WEST. - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  10. The Revival of Research Circles: Meeting the Needs of Modern Aging and the Third Age

    ERIC Educational Resources Information Center

    Ostlund, Britt

    2008-01-01

    This article provides evidence that it is worthwhile to reconsider the traditional research circle method as a means of involving people in the third age in fulfilling their needs to participate in learning activities and make their voices heard. The findings are based on three cases of research circles consistently driven by the interests of the…

  11. Comparing Interactions in Literature Circles in Both Online and in Class Discussions

    ERIC Educational Resources Information Center

    Skeen, Christel Ghrist

    2014-01-01

    Discourse analysis of literature circles can lead educators to understand the different types of interactions taking place as students talk about text. Social and academic interactions exist in both face-to-face and online discussions of reading material. This study examines two different settings of literature circles and compares interactions of…

  12. Young Puerto Rican Children's Exploration of Racial Discourses within the Figured Worlds of Literature Circles

    ERIC Educational Resources Information Center

    Castrodad-Rodriguez, Patricia Margarita

    2010-01-01

    This study examines the racial discourses of six and seven year old Puerto Rican children participating in small group literature circles over one academic year. The main research question is "How do Puerto Rican young children in a multiage classroom construct race through dialogue within the figured worlds of literature circles?" This study…

  13. Collaborative Inquiry in Reading Recovery, or "Why Sit in a Circle?"

    ERIC Educational Resources Information Center

    Rodgers, Emily

    2000-01-01

    In Reading Recovery, training participants sit in a circle to discuss lessons that have been communally observed. The rationale for sitting in a circle without a table for discussion can be better understood by considering these two ideas: (1) the role of language in learning; and (2) the way conversation is affected by the physical positioning of…

  14. Table or Circles: A Comparison of Two Methods for Choosing among Career Alternatives

    ERIC Educational Resources Information Center

    Amit, Adi; Gati, Itamar

    2013-01-01

    A sample of 182 young adults about to choose their college major were randomly assigned to 2 guidance methods aimed at facilitating choosing among promising career alternatives: Table-for-Choice and Circles-for-Choice. Table-for-Choice was perceived as more effective, but individuals' confidence in their choice was higher in the Circles-for-Choice…

  15. From Silence to a Whisper to Active Participation: Using Literature Circles with ELL Students

    ERIC Educational Resources Information Center

    Carrison, Catherine; Ernst-Slavit, Gisela

    2005-01-01

    This article discusses benefits of using literature circles with ELL students to strengthen literacy skills and student confidence. Highlighting one teacher's implementation of literature circles, the authors present a candid examination of areas of initial weakness and describe strategies used for improvements in subsequent "rounds." A discussion…

  16. Improving the Reading Attitudes of College Students: Using Literature Circles to Learn about Content Reading

    ERIC Educational Resources Information Center

    Bernadowski, Carianne

    2013-01-01

    Literature circles and book clubs have become a popular instructional literacy strategy. In recent years, educators attempt to motivate students to read more in quantity and quality at an early age. A case study design was utilized that required undergraduate education majors to participate in literature circles reading historical fiction and…

  17. Providing a Full Circle of Support to Teachers in an Inclusive Elementary School

    ERIC Educational Resources Information Center

    Waldron, Nancy L.; Redd, Lacy

    2011-01-01

    Providing a full circle of support to teachers in an inclusive elementary school, the Newberry Elementary School (NES) principal and staff have worked for 5 years to ensure the inclusion of students with disabilities in general education classrooms. The authors would like to share their perceptions of how this full circle (the multiple systems) of…

  18. 77 FR 55691 - Establishment of Class E Airspace; Circle Town, MT

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-11

    ... (RNAV) Global Positioning System (GPS) standard instrument approach procedures at Circle Town County... Circle Town, MT (77 FR 39651). Interested parties were invited to participate in this rulemaking effort... a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26,...

  19. Report of a Study of the Pacific Circle Consortium. [Final Report].

    ERIC Educational Resources Information Center

    Kemmis, Stephen

    A five-part cumulative report details the activities of the Pacific Circle Consortium. Section 1, on the origins of the Pacific Circle, describes the consortium on three levels: participating organization of Economic Cooperation and Development (OECD) countries, participating institutions, and development teams. In section 2, the involvement of…

  20. Laying the Groundwork for the Effective Implementation of Quality Circles in a Community College.

    ERIC Educational Resources Information Center

    Ruff, Dan

    This five-part paper provides an overview of the use of quality circles as a participative management technique in community colleges. Section I offers an introduction to the technique, reviewing the history of quality circles from their development in Japan in the early 1960s to their introduction in American higher education in the early 1980s.…

  1. A Rolling Circle Replication Mechanism Produces Multimeric Lariats of Mitochondrial DNA in Caenorhabditis elegans

    PubMed Central

    Lewis, Samantha C.; Joers, Priit; Willcox, Smaranda; Griffith, Jack D.; Jacobs, Howard T.; Hyman, Bradley C.

    2015-01-01

    Mitochondrial DNA (mtDNA) encodes respiratory complex subunits essential to almost all eukaryotes; hence respiratory competence requires faithful duplication of this molecule. However, the mechanism(s) of its synthesis remain hotly debated. Here we have developed Caenorhabditis elegans as a convenient animal model for the study of metazoan mtDNA synthesis. We demonstrate that C. elegans mtDNA replicates exclusively by a phage-like mechanism, in which multimeric molecules are synthesized from a circular template. In contrast to previous mammalian studies, we found that mtDNA synthesis in the C. elegans gonad produces branched-circular lariat structures with multimeric DNA tails; we were able to detect multimers up to four mtDNA genome unit lengths. Further, we did not detect elongation from a displacement-loop or analogue of 7S DNA, suggesting a clear difference from human mtDNA in regard to the site(s) of replication initiation. We also identified cruciform mtDNA species that are sensitive to cleavage by the resolvase RusA; we suggest these four-way junctions may have a role in concatemer-to-monomer resolution. Overall these results indicate that mtDNA synthesis in C. elegans does not conform to any previously documented metazoan mtDNA replication mechanism, but instead are strongly suggestive of rolling circle replication, as employed by bacteriophages. As several components of the metazoan mitochondrial DNA replisome are likely phage-derived, these findings raise the possibility that the rolling circle mtDNA replication mechanism may be ancestral among metazoans. PMID:25693201

  2. Social constructions of the male contraception pill: When are we going to break the vicious circle?

    PubMed

    Dismore, Lorelle; Van Wersch, Anna; Swainston, Katherine

    2016-05-01

    Social constructions of men towards the availability of a male hormonal contraceptive, the 'male pill', were explored. A qualitative approach applying semi-structured interviews and scenarios with 22 men (mean age 35 years) from the North East of England revealed two core constructs and six sub-constructs using a Thematic-Construct Analysis in line with the method of Toerien and Wilkinson and Clarke and Kitzinger. Verbal accounts were inductively used to balance the deductively created two core constructs 'Constructing the male pill norm: dominant system of sensemaking' and 'Living by the male pill norm' to represent a normative framework within a changing ideology of shared responsibility in contraceptive choice. Constructing the male pill norm was divided into two sub-constructs: 'Male pill: we are going to join the women and become responsible - too!' and 'Male pill: you look so girly - what are they going to think of me?' The 'Living by the male pill norm' was further divided into four sub-constructs 'Male pill - thank you for giving me promises not to have to become a dad as yet!'; 'Male pill: thank you for the idea of fun - sorry about my morals!'; 'Male pill: in stable relations - yes, I would have you now - sorry, I am too late!' and 'Male pill, we love you - but we are too anxious - we are not ready as yet!' From this male discourse, it is clear that discussions over the male pill follow the line of a vicious circle. In order to establish long-term side effects, Phase IV studies are necessary, and these cannot commence without the male hormonal contraception being a marketable product. So, unless this circle gets broken by some brave men, the male pill will remain a virtual rotating idea for a long time. PMID:24997170

  3. A new method for fast circle detection in a complex background image

    NASA Astrophysics Data System (ADS)

    Wu, Meijun; Yang, Jie; Sun, Yadong

    2011-11-01

    A new method for circle detection, Hough gradient clustering method, has been developed in this paper. By using gradient direction angle to find the diameter of a circle, the new method can rapidly detect the circle in a complex background. The crucial steps in this method are the feature extraction and the clustering of the points which have the same gray direction angle and are collinear along the gradient direction. The application of the two-to-one space mapping and 1-2Hough transform can further reduce the useless calculation in the process of circle detection. Comparing with the Hough gradient method in OpenCV, the newly developed method shows a higher efficiency of circle detection in a complex background image as well as a great improvement in the anti-noise ability.

  4. Conformal foliations by circles and complex isoparametric functions on Euclidean 3-space

    NASA Astrophysics Data System (ADS)

    Baird, P.

    1998-03-01

    The space of circles in S3 completed to include points is identified with a complex quadric hypersurface [script H] of CP4. A conformal foliation by arcs of circles of a domain in R3 now corresponds to a complex holomorphic curve in [script H]. The space [script H] minus a hyperplane section fibres in a natural way over the space of lines in R3, each fibre consisting of the well known family of circles of Villarceau transformed by a homothety. As a consequence we show that there is a correspondence between harmonic morphisms on the 3-dimensional space forms and demonstrate the existence of a distinguished surface associated to a conformal foliation by arcs of circles.We generalize Cartan's isoparametric functions to complex valued functions and classify all those horizontally conformal complex isoparametric functions defined on domains of R3 with arcs of circles or lines as fibres.

  5. Monte Carlo method based radiative transfer simulation of stochastic open forest generated by circle packing application

    NASA Astrophysics Data System (ADS)

    Jin, Shengye; Tamura, Masayuki

    2013-10-01

    Monte Carlo Ray Tracing (MCRT) method is a versatile application for simulating radiative transfer regime of the Solar - Atmosphere - Landscape system. Moreover, it can be used to compute the radiation distribution over a complex landscape configuration, as an example like a forest area. Due to its robustness to the complexity of the 3-D scene altering, MCRT method is also employed for simulating canopy radiative transfer regime as the validation source of other radiative transfer models. In MCRT modeling within vegetation, one basic step is the canopy scene set up. 3-D scanning application was used for representing canopy structure as accurately as possible, but it is time consuming. Botanical growth function can be used to model the single tree growth, but cannot be used to express the impaction among trees. L-System is also a functional controlled tree growth simulation model, but it costs large computing memory. Additionally, it only models the current tree patterns rather than tree growth during we simulate the radiative transfer regime. Therefore, it is much more constructive to use regular solid pattern like ellipsoidal, cone, cylinder etc. to indicate single canopy. Considering the allelopathy phenomenon in some open forest optical images, each tree in its own `domain' repels other trees. According to this assumption a stochastic circle packing algorithm is developed to generate the 3-D canopy scene in this study. The canopy coverage (%) and the tree amount (N) of the 3-D scene are declared at first, similar to the random open forest image. Accordingly, we randomly generate each canopy radius (rc). Then we set the circle central coordinate on XY-plane as well as to keep circles separate from each other by the circle packing algorithm. To model the individual tree, we employ the Ishikawa's tree growth regressive model to set the tree parameters including DBH (dt), tree height (H). However, the relationship between canopy height (Hc) and trunk height (Ht) is

  6. ULYSSES comes full circle, before revisiting the Sun's poles

    NASA Astrophysics Data System (ADS)

    1998-04-01

    From its unique perspective, Ulysses has provided scientists with the very first all-round map of the heliosphere, the huge bubble in space filled by the Sun's wind. The Earth swims deep inside the heliosphere, and gusts and shocks in the solar wind can harm satellites, power supplies and ommunications. They may also affect our planet's weather. A better grasp of the solar weather in the heliosphere is therefore one of the major aims of ESA's science programme. In a project of international cooperation between ESA and NASA, Ulysses was launched towards Jupiter in October 1990 by the US space shuttle Discovery. Arriving in February 1992, Ulysses stole energy from the giant planet in a slingshot manoeuvre and was propelled back towards the Sun in an elongated orbit almost at right angles to the ecliptic plane, where the Earth and other planets circle the Sun. "This month Ulysses returns to the point in space where its out-of-ecliptic journey began, but Jupiter isn't there," explains Richard Marsden, ESA's project scientist for Ulysses. "Following its own inexorable path around the Sun, Jupiter is far away on the opposite side of the Solar System. So Ulysses' course will not be changed a second time. The spacecraft is now in effect a man-made comet, forever bound into a 6-year polar orbit around the Sun." Ulysses now starts its second orbit. It will travel over the poles of the Sun in 2000-2001 just as the count of dark sunspots is expected to reach a maximum. With its operational life extended for the Ulysses Solar Maximum Mission, the spacecraft will find the heliosphere much stormier than during its first orbit. Discoveries so far Like its mythical namesake, Ulysses has already had an eventful voyage of discovery. Its unique trajectory has provided the scientific teams with a new perspective, from far out in space and especially in the previously unknown regions of the heliosphere over the Sun's poles. Passing within 9.8 degrees of the polar axis, the highly

  7. Localized vegetation patterns, fairy circles, and localized patches in arid landscapes

    NASA Astrophysics Data System (ADS)

    Escaff, D.; Fernandez-Oto, C.; Clerc, M. G.; Tlidi, M.

    2015-02-01

    We investigate the formation of localized structures with varying widths in one- and two-dimensional systems. The mechanism of stabilization is attributed to strongly nonlocal coupling mediated by a Lorentzian type of kernel. We show that, in addition to stable dips found recently [see, e.g. Fernandez-Oto et al., Phys. Rev. Lett. 110, 174101 (2013), 10.1103/PhysRevLett.110.174101], there are stable localized peaks which appear as a result of strongly nonlocal coupling. We applied this mechanism to arid ecosystems by considering a prototype model of a Nagumo type. In one dimension, we study the front connecting the stable uniformly vegetated state to the bare one under the effect of strongly nonlocal coupling. We show that strongly nonlocal coupling stabilizes both—dip and peak—localized structures. We show analytically and numerically that the width of a localized structure, which we interpret as a fairy circle, increases strongly with the aridity parameter. This prediction is in agreement with published observations. In addition, we predict that the width of localized patch decreases with the degree of aridity. Numerical results are in close agreement with analytical predictions.

  8. "Quality Circles": A Strategy for Personal and Curriculum Development. Coombe Lodge Working Paper. Information Bank Number 1803.

    ERIC Educational Resources Information Center

    Field, M. J.; Harrison, A. B.

    Quality circles attempt to satisfy both task and personal needs through staff involvement in solving work-related problems. This paper summarizes quality circle theory, applies it to school settings, and suggests a framework for introducing the process to educational institutions. After briefly defining quality circles, the article presents two…

  9. Kinetics of the forelimb in horses circling on different ground surfaces at the trot.

    PubMed

    Chateau, Henry; Camus, Mathieu; Holden-Douilly, Laurène; Falala, Sylvain; Ravary, Bérangère; Vergari, Claudio; Lepley, Justine; Denoix, Jean-Marie; Pourcelot, Philippe; Crevier-Denoix, Nathalie

    2013-12-01

    Circling increases the expression of distal forelimb lameness in the horse, depending on rein, diameter and surface properties of the circle. However, there is limited information about the kinetics of horses trotting on circles. The aim of this study was to quantify ground reaction force (GRF) and moments in the inside and outside forelimb of horses trotting on circles and to compare the results obtained on different ground surfaces. The right front hoof of six horses was equipped with a dynamometric horseshoe, allowing the measurement of 3-dimensional GRF, moments and trajectory of the centre of pressure. The horses were lunged at slow trot (3 m/s) on right and left 4 m radius circles on asphalt and on a fibre sand surface. During circling, the inside forelimb produced a smaller peak vertical force and the stance phase was longer in comparison with the outside forelimb. Both right and left circling produced a substantial transversal force directed outwards. On a soft surface (sand fibre), the peak transversal force and moments around the longitudinal and vertical axes of the hoof were significantly decreased in comparison with a hard surface (asphalt). Sinking of the lateral or medial part of the hoof in a more compliant surface enables reallocation of part of the transversal force into a proximo-distal force, aligned with the limb axis, thus limiting extrasagittal stress on the joints. PMID:24511634

  10. Hypomagnesemia in Type 2 Diabetes: A Vicious Circle?

    PubMed

    Gommers, Lisanne M M; Hoenderop, Joost G J; Bindels, René J M; de Baaij, Jeroen H F

    2016-01-01

    Over the past decades, hypomagnesemia (serum Mg(2+) <0.7 mmol/L) has been strongly associated with type 2 diabetes mellitus (T2DM). Patients with hypomagnesemia show a more rapid disease progression and have an increased risk for diabetes complications. Clinical studies demonstrate that T2DM patients with hypomagnesemia have reduced pancreatic β-cell activity and are more insulin resistant. Moreover, dietary Mg(2+) supplementation for patients with T2DM improves glucose metabolism and insulin sensitivity. Intracellular Mg(2+) regulates glucokinase, KATP channels, and L-type Ca(2+) channels in pancreatic β-cells, preceding insulin secretion. Moreover, insulin receptor autophosphorylation is dependent on intracellular Mg(2+) concentrations, making Mg(2+) a direct factor in the development of insulin resistance. Conversely, insulin is an important regulator of Mg(2+) homeostasis. In the kidney, insulin activates the renal Mg(2+) channel transient receptor potential melastatin type 6 that determines the final urinary Mg(2+) excretion. Consequently, patients with T2DM and hypomagnesemia enter a vicious circle in which hypomagnesemia causes insulin resistance and insulin resistance reduces serum Mg(2+) concentrations. This Perspective provides a systematic overview of the molecular mechanisms underlying the effects of Mg(2+) on insulin secretion and insulin signaling. In addition to providing a review of current knowledge, we provide novel directions for future research and identify previously neglected contributors to hypomagnesemia in T2DM. PMID:26696633

  11. Pervasive Horizontal Transfer of Rolling-Circle Transposons among Animals

    PubMed Central

    Thomas, Jainy; Schaack, Sarah; Pritham, Ellen J.

    2010-01-01

    Horizontal transfer (HT) of genes is known to be an important mechanism of genetic innovation, especially in prokaryotes. The impact of HT of transposable elements (TEs), however, has only recently begun to receive widespread attention and may be significant due to their mutagenic potential, inherent mobility, and abundance. Helitrons, also known as rolling-circle transposons, are a distinctive subclass of TE with a unique transposition mechanism. Here, we describe the first evidence for the repeated HT of four different families of Helitrons in an unprecedented array of organisms, including mammals, reptiles, fish, invertebrates, and insect viruses. The Helitrons present in these species have a patchy distribution and are closely related (80–98% sequence identity), despite the deep divergence times among hosts. Multiple lines of evidence indicate the extreme conservation of sequence identity is not due to selection, including the highly fragmented nature of the Helitrons identified and the lack of any signatures of selection at the nucleotide level. The presence of horizontally transferred Helitrons in insect viruses, in particular, suggests that this may represent a potential mechanism of transfer in some taxa. Unlike genes, Helitrons that have horizontally transferred into new host genomes can amplify, in some cases reaching up to several hundred copies and representing a substantial fraction of the genome. Because Helitrons are known to frequently capture and amplify gene fragments, HT of this unique group of DNA transposons could lead to horizontal gene transfer and incur dramatic shifts in the trajectory of genome evolution. PMID:20693155

  12. Molecular identification of Histoplasma capsulatum using rolling circle amplification.

    PubMed

    Furuie, Jason L; Sun, Jiufeng; do Nascimento, Mariana M F; Gomes, Renata R; Waculicz-Andrade, Caroline E; Sessegolo, Gisele C; Rodrigues, Anderson M; Galvão-Dias, Maria A; de Camargo, Zoilo P; Queiroz-Telles, Flávio; Najafzadeh, Mohammad J; de Hoog, Sybren G; Vicente, Vania A

    2016-01-01

    Histoplasmosis is a systemic fungal disease that occurs worldwide, causing symptomatic infection mostly in immunocompromised hosts. Etiological agent is the dimorphic fungus, Histoplasma capsulatum, which occurs in soil contaminated with bird or bat droppings. Major limitation in recognition of H. capsulatum infections is the low awareness, since other diseases may have similar symptomatology. The molecular methods have gained importance because of unambiguous diagnostic ability and efficiency. The aim of this study was to develop and evaluate a padlock probe in view of rolling circle amplification (RCA) detection method which targets ITS (Internal Transcribed Spacer) rDNA of H. capsulatum enabling rapid and specific detection of the fungus in clinical samples. Two padlock probes were designed and one of these (HcPL2) allowed specific amplification of H. capsulatum DNA while no cross-reactivity was observed with fungi used as negative controls. This method proved to be effective for H. capsulatum specific identification and demonstrated to be faster than the traditional method of microbiological identification. PMID:26578301

  13. Investigations on the radially free full circle arc

    NASA Astrophysics Data System (ADS)

    Tiller, W.

    1981-07-01

    The hypothesis that the steady state of a magnetically deflected arc is determined by the equilibrium of the thermodynamic and the magnetohydrodynamic forces is experimentally investigated. An argon arc, burning between two horizontal plane-parallel, insulating plates, bent circularly by its own and an external magnetic field, provided the well-defined conditions by giving a stationary, radially free, full circle arc for the experimental investigation. The local temperature distributions in the arc cross-section were detected spectroscopically as functions of the arc current and the arc radius or curvature. The mass flow field in the arc was determined using basic equations of conservation of energy, mass, and charge, and the known transport parameters of argon at atmospheric pressure. The results represented as a stream line graph, show a symmetric quadruple whirl instead of the expected double whirl, suggested to be due to experimental conditions. The equilibrium of heating and cooling mechanisms inside a curved arc and the relative motion of mass and arc were demonstrated. Experimental and theoretical data are in good agreement.

  14. Complex velocity potential for an ellipse and a circle in translation and rotation

    NASA Astrophysics Data System (ADS)

    Sun, R.; Chwang, A. T.

    1997-12-01

    This paper investigates the analytical solutions of two-dimensional Neumann-type external boundary-value problem for an ellipse and a circle in complex analysis treatment. The transformation of harmonics between two planes is expanded in Laurent series. The circle theorem is extended so as to suit to the system of the ellipse and the circle. By means of Basset's process, the harmonic expressions of the system are found in the form of recurrence formulae which are suitable for numerical computations. The complex velocity potential of the system in translation and rotation is represented by the summation of the harmonic expressions.

  15. Two-dimensional gel analysis of rolling circle replication in the presence and absence of bacteriophage T4 primase.

    PubMed Central

    Belanger, K G; Mirzayan, C; Kreuzer, H E; Alberts, B M; Kreuzer, K N

    1996-01-01

    The rolling circle DNA replication structures generated by the in vitro phage T4 replication system were analyzed using two-dimensional agarose gels. Replication structures were generated in the presence or absence of T4 primase (gp61), permitting the analysis of replication forks with either duplex or single-stranded tails. A characteristic arc shape was visualized when forks with single-stranded tails were cleaved by a restriction enzyme with the help of an oligonucleotide that anneals to restriction sites in the single-stranded tail. After calibrating the gel system with this well-studied rolling circle replication reaction, we then analyzed the in vivo replication directed by a T4 replication origin cloned within a plasmid. DNA samples were generated from infections with either wild-type or primase-deletion mutant phage. The only replicative arc that could be detected in the wild-type sample corresponded to duplex Y forms, consistent with very efficient lagging strand synthesis. Surprisingly, we obtained evidence for both duplex and single-stranded DNA tails in the samples from the primase-deficient infection. We conclude that a relatively inefficient mechanism primes lagging strand DNA synthesis in vivo when gp61 is absent. PMID:8668550

  16. A route to computational chaos revisited: noninvertibility and the breakup of an invariant circle

    NASA Astrophysics Data System (ADS)

    Frouzakis, Christos E.; Kevrekidis, Ioannis G.; Peckham, Bruce B.

    2003-03-01

    In a one-parameter study of a noninvertible family of maps of the plane arising in the context of a numerical integration scheme, Lorenz studied a sequence of transitions from an attracting fixed point to “computational chaos”. As part of the transition sequence, he proposed the following as a possible scenario for the breakup of an invariant circle (IC): the IC develops regions of increasingly sharper curvature until at a critical parameter value it develops cusps; beyond this parameter value, the IC fails to persist, and the system exhibits chaotic behavior on an invariant set with loops [Computational chaos-a prelude to computational instability, Physica D 35 (1989) 299]. We investigate this problem in more detail and show that the IC is actually destroyed in a global bifurcation before it has a chance to develop cusps. Instead, the global unstable manifolds of saddle-type periodic points are the objects which develop cusps and subsequently “loops” or “antennae”. The one-parameter study is better understood when embedded in the full two-parameter space and viewed in the context of the two-parameter Arnold horn structure. Certain elements of the interplay of noninvertibility with this structure, the associated ICs, periodic points and global bifurcations are examined.

  17. Design of Novel Relaxase Substrates Based on Rolling Circle Replicases for Bioconjugation to DNA Nanostructures

    PubMed Central

    Sagredo, Sandra; de la Cruz, Fernando; Moncalián, Gabriel

    2016-01-01

    During bacterial conjugation and rolling circle replication, HUH endonucleases, respectively known as relaxases and replicases, form a covalent bond with ssDNA when they cleave their target sequence (nic site). Both protein families show structural similarity but limited amino acid identity. Moreover, the organization of the inverted repeat (IR) and the loop that shape the nic site differs in both proteins. Arguably, replicases cleave their target site more efficiently, while relaxases exert more biochemical control over the process. Here we show that engineering a relaxase target by mimicking the replicase target, results in enhanced formation of protein-DNA covalent complexes. Three widely different relaxases, which belong to MOBF, MOBQ and MOBP families, can properly cleave DNA sequences with permuted target sequences. Collaterally, the secondary structure that the permuted targets acquired within a supercoiled plasmid DNA resulted in poor conjugation frequencies underlying the importance of relaxase accessory proteins in conjugative DNA processing. Our results reveal that relaxase and replicase targets can be interchangeable in vitro. The new Rep substrates provide new bioconjugation tools for the design of sophisticated DNA-protein nanostructures. PMID:27027740

  18. Fast and accurate circle detection using gradient-direction-based segmentation.

    PubMed

    Wu, Jianping; Chen, Ke; Gao, Xiaohui

    2013-06-01

    We present what is to our knowledge the first-ever fitting-based circle detection algorithm, namely, the fast and accurate circle (FACILE) detection algorithm, based on gradient-direction-based edge clustering and direct least square fitting. Edges are segmented into sections based on gradient directions, and each section is validated separately; valid arcs are then fitted and further merged to extract more accurate circle information. We implemented the algorithm with the C++ language and compared it with four other algorithms. Testing on simulated data showed FACILE was far superior to the randomized Hough transform, standard Hough transform, and fast circle detection using gradient pair vectors with regard to processing speed and detection reliability. Testing on publicly available standard datasets showed FACILE outperformed robust and precise circular detection, a state-of-art arc detection method, by 35% with regard to recognition rate and is also a significant improvement over the latter in processing speed. PMID:24323106

  19. Introduction of the carbon dioxide absorption method with closed circle breathing into anesthesia practice.

    PubMed

    Foregger, R

    2000-07-01

    The circle breathing CO2 absorption system for use during acetylene anesthesia was described by Carl Gauss in 1924/1925. The apparatus was manufactured by Drägerwerk of Lübeck. A considerable number of publications on the apparatus employing the closed circle method of CO2 absorption appeared in the medical press soon thereafter. Later apparatus models, also built by Drägerwerk, were adapted for nitrous oxide-oxygen-ether anesthesia and introduced into practice by Paul Sudeck and Helmut Schmidt. Information about all this was transmitted to America through the German medical press, including the Draeger-Hefte. American anesthesia machine manufacturers began to develop closed circle CO2 absorbers several years later. Claims that the circle breathing CO2 absorption method was introduced into anesthesia practice by Brian Sword are not valid. PMID:10969391

  20. Sister Circles as a Culturally Relevant Intervention for Anxious African American Women

    PubMed Central

    Neal-Barnett, Angela; Stadulis, Robert; Murray, Marsheena; Payne, Margaret Ralston; Thomas, Anisha; Salley, Bernadette B.

    2011-01-01

    Research on anxiety treatment with African American women reveals a need to develop interventions that address factors relevant to their lives. Such factors include feelings of isolation, multiple roles undertaken by Black women, and faith. A recurrent theme across treatment studies is the importance of having support from other Black women. Sister circles are support groups that build upon existing friendships, fictive kin networks, and the sense of community found among African Americans females. Sister circles appear to offer many of the components Black women desire in an anxiety intervention. In this article, we explore sister circles as an intervention for anxious African American women. Culturally-infused aspects from our sister circle work with middle-class African American women are presented. Further research is needed. PMID:22081747

  1. Visual Thinking, Algebraic Thinking, and a Full Unit-Circle Diagram.

    ERIC Educational Resources Information Center

    Shear, Jonathan

    1985-01-01

    The study of trigonometric functions in terms of the unit circle offer an example of how students can learn algebraic relations and operations while using visually oriented thinking. Illustrations are included. (MNS)

  2. DINE-1, the highest copy number repeats in Drosophila melanogaster are non-autonomous endonuclease-encoding rolling-circle transposable elements (Helentrons)

    PubMed Central

    2014-01-01

    Background The Drosophila INterspersed Elements-1 (DINE-1/INE1) transposable elements (TEs) are the most abundant component of the Drosophila melanogaster genome and have been associated with functional gene duplications. DINE-1 TEs do not encode any proteins (non-autonomous) thus are moved by autonomous partners. The identity of the autonomous partners has been a mystery. They have been allied to Helitrons (rolling-circle transposons), MITEs (DNA transposons), and non-LTR retrotransposons by different authors. Results We report multiple lines of bioinformatic evidence that illustrate the relationship of DINE-1 like TEs to endonuclease-encoding rolling-circle TEs (Helentrons). The structural features of Helentrons are described, which resemble the organization of the non-autonomous partners, but differ significantly from canonical Helitrons. In addition to the presence of an endonuclease domain fused to the Rep/Helicase protein, Helentrons have distinct structural features. Evidence is presented that illustrates that Helentrons are widely distributed in invertebrate, fish, and fungal genomes. We describe an intermediate family from the Phytophthora infestans genome that phylogenetically groups with Helentrons but that displays Helitron structure. In addition, evidence is presented that Helentrons can capture gene fragments in a pattern reminiscent of canonical Helitrons. Conclusions We illustrate the relationship of DINE-1 and related TE families to autonomous partners, the Helentrons. These findings will allow their proper classification and enable a more accurate understanding of the contribution of rolling-circle transposition to the birth of new genes, gene networks, and genome composition. PMID:24959209

  3. Fostering Positive Peer Relations in the Primary Classroom through Circle Time and Co-Operative Games

    ERIC Educational Resources Information Center

    Mary, Latisha

    2014-01-01

    The aim of this study was to investigate the role of co-operative games and circle time activities in fostering positive peer relations in two French Primary classrooms (N = 40). It presents French teachers' and pupils' perceptions of a set of co-operative games and circle time activities implemented within a year long study on personal,…

  4. VizieR Online Data Catalog: W1J00 and W2J00 Transit Circle Catalogs (Rafferty+, 2016)

    NASA Astrophysics Data System (ADS)

    Rafferty, T. J.; Holdenried, E. R.; Urban, S. E.

    2016-06-01

    The W1J00, named because it was the first (of two) Washington transit circle catalog to be referred to the Equinox of J2000.0, is the result of observations made with the Six-inch Transit Circle in Washington, D.C., between September 1977 and July 1982. The observing program was structured to be absolute, in the sense that the positions were not explicitly relying on any previous observations. The absolute positions were defined with respect to an internally consistent frame that was unique to the particular instrument. Following the reductions, comparisons with stars from the Hipparcos Catalogue (European Space Agency 1997) revealed unaccounted for systematic differences on the level of 100-200mas. It was decided, therefore, to include data on both the absolute positions reduced in way common to many past Washington transit circle catalogs, as well as the positions differentially adjusted to the system of the Hipparcos Catalog. The W1J00 contains mean positions of 7267 stars and 4383 observations of solar system objects. The majority of the stars fall into two categories; those from the Fifth Fundamental Catalog (FK5; Fricke et al 1988), and those from the Catalog Of 3539 Zodiacal Stars For The Equinox 1950.0 (Robertson 1940). The solar system objects include the Sun, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, eight minor planets (Eunomia, Flora, Hebe, Iris, Juno, Metis, Pallas, and Vesta), and the dwarf planet Ceres. Characteristics of the W1J00 catalog: Category Range Average ------------------------------------------------------------- Magnitudes -1.6 to 10.4 7.18 RA standard errors of the mean 15 to 460 mas 98 mas Dec standard errors of the mean 10 to 400 mas 107 mas RA Number of observations / star 3 to 187 10 Dec Number of observations / star 2 to 179 10 Declination coverage -39 to +90 degrees ------------------------------------------------------------- Details of the W1J00 can be found in Rafferty, Holdenried, and Urban (2016, Publ. USNO, 2nd

  5. Numerical analysis for hydrodynamic interaction effects between vessel and semi-circle bank wall

    NASA Astrophysics Data System (ADS)

    Lee, Chun-Ki; Moon, Serng-Bae; Oh, Jin-Seok; Lee, Sang-Min

    2015-07-01

    The hydrodynamic interaction forces and moments induced by the vicinity of bank on a passing vessel are known as wall effects. In this paper, the characteristics of interaction acting on a passing vessel in the proximity of a semi-circle bank wall are described and illustrated, and the effects of ship velocity, water depth and the lateral distance between vessel and semi-circle bank wall are discussed. For spacing between ship and semi-circle bank wall (SP) less than about 0.2 L and depth to ship's draft ratio (h/d) less than around 2.0, the ship-bank interaction effects increase steeply as h/d decreases. However, for spacing between ship and semi-circle bank wall (SP) more than about 0.3 L, the ship-bank interaction effects increase slowly as h/d decreases, regardless of the water depth. Also, for spacing between ship and semi-circle bank wall (SP) less than about 0.2 L, the hydrodynamic interaction effects acting on large vessel increase largely as ship velocity increases. In the meantime, for spacing between ship and semi-circle bank wall (SP) more than 0.3 L, the interaction effects increase slowly as ship velocity increases.

  6. A Voyage around the Recumbent Stone Circles of North-East Scotland

    NASA Astrophysics Data System (ADS)

    Henty, Liz

    2015-05-01

    This paper details new archaeoastronomical research undertaken at the Recumbent Stone Circles (RSCs) of Scotland. Research to date has concentrated on the recumbent arrangement and the major theorists such as Thom, Ruggles and Burl, proposed that the recumbent and pillars are aligned to the lunar standstills or the passage of the moon over the recumbent. This research took a different voyage around the circles, which included checking all the stones of the circle for solar and stellar alignments as well as lunar alignments. It looks at nine RSCs, using both new plans drawn up by RCAHMS and plans published by Thom. The research was prompted by preliminary research, reported on at SEAC 2010, which detailed fieldwork completed at three sites. Because of the earlier focus on the recumbent, the RSCs have generally been interpreted in terms of a lunar narrative. By contrast, the aims of this research were to examine the circle in its entirety examining each circle stone for possible solar, lunar and stellar alignments using the dates of 2500 BC and 2000 BC. The results for all the circle stones showed that there were just as many solar as lunar alignments and that some stellar alignments may have been important symbolically.

  7. Geomorphic domains and linear features on Landsat images, Circle Quadrangle, Alaska

    USGS Publications Warehouse

    Simpson, S.L.

    1984-01-01

    A remote sensing study using Landsat images was undertaken as part of the Alaska Mineral Resource Assessment Program (AMRAP). Geomorphic domains A and B, identified on enhanced Landsat images, divide Circle quadrangle south of Tintina fault zone into two regional areas having major differences in surface characteristics. Domain A is a roughly rectangular, northeast-trending area of relatively low relief and simple, widely spaced drainages, except where igneous rocks are exposed. In contrast, domain B, which bounds two sides of domain A, is more intricately dissected showing abrupt changes in slope and relatively high relief. The northwestern part of geomorphic domain A includes a previously mapped tectonostratigraphic terrane. The southeastern boundary of domain A occurs entirely within the adjoining tectonostratigraphic terrane. The sharp geomorphic contrast along the southeastern boundary of domain A and the existence of known faults along this boundary suggest that the southeastern part of domain A may be a subdivision of the adjoining terrane. Detailed field studies would be necessary to determine the characteristics of the subdivision. Domain B appears to be divisible into large areas of different geomorphic terrains by east-northeast-trending curvilinear lines drawn on Landsat images. Segments of two of these lines correlate with parts of boundaries of mapped tectonostratigraphic terranes. On Landsat images prominent north-trending lineaments together with the curvilinear lines form a large-scale regional pattern that is transected by mapped north-northeast-trending high-angle faults. The lineaments indicate possible lithlogic variations and/or structural boundaries. A statistical strike-frequency analysis of the linear features data for Circle quadrangle shows that northeast-trending linear features predominate throughout, and that most northwest-trending linear features are found south of Tintina fault zone. A major trend interval of N.64-72E. in the linear

  8. Gene analysis of signal-joint T cell receptor excision circles and their relationship to age in dogs.

    PubMed

    Ito, Genta; Yoshimura, Kuniko; Momoi, Yasuyuki

    2015-07-15

    The quantification of DNA excision circles produced during T cell receptor (TCR) rearrangement, termed signal joint TCR rearrangement excision circles (sjTRECs), has been employed as a measure of age and thymic function in humans and animals. δRec-ψJα sjTRECs are ring-shaped DNAs that are generated during TCRδ locus deletion that occurs at a late stage of T cell development. In this study, the nucleotide sequences of δRec-ψJα signal joints of canine δRec-ψJα sjTRECs were analyzed. The gene structure of canine δRec-ψJα signal joints was found to be similar to that of humans and mice. However, diversity of signal joints was detected and found to derive from N nucleotide insertions, recombination signal sequence combinational diversity and single-base substitutions at the recombination signal sequence. In addition, an adenine insertion or deletion was found approximately 280 bases from the ψJα signal end. Blood samples were collected from 46 dogs, ranging in age from 3 to 192 months, with a mean age of 96.4 and a SD of 51.5 months. Although δRec-ψJα sjTRECs were detectable in most of the dogs evaluated, the level did not significantly correlate with age. These results indicated that δRec-ψJα sjTREC levels were ineffective as a measure of age in dogs. PMID:26004946

  9. An aptamer assay using rolling circle amplification coupled with thrombin catalysis for protein detection.

    PubMed

    Guo, Limin; Hao, Lihua; Zhao, Qiang

    2016-07-01

    We describe a sensitive aptamer-based sandwich assay for protein detection on microplate by using rolling circle amplification (RCA) coupled with thrombin catalysis. This assay takes advantage of RCA generating long DNA oligonucleotides with repeat thrombin-binding aptamer sequence, specific aptamer affinity binding to achieve multiple thrombin labeling, and enzyme activity of thrombin for signal generation. Protein target is specifically captured by antibody-coated microplate. Then, an oligonucleotide containing an aptamer for protein and a primer sequence is added to form a typical sandwich structure. Following a template encoded with complementary sequence of aptamer for thrombin, RCA reaction extends the primer sequence into a long oligonucleotide. Many thrombin molecules bind with the RCA product. Thrombin catalyzes the conversion of its chromogenic or fluorogenic peptide substrates into detectable products for final quantification of protein targets. We applied this strategy to the detection of a model protein target, platelet-derived growth factor-BB (PDGF-BB). Due to double signal amplifications from RCA and thrombin catalysis, this assay enabled the detection of PDGF-BB as low as 3.1 pM when a fluorogenic peptide substrate was used. This assay provides a new way for signal generation in RCA-involved assay through direct thrombin labeling, circumventing time-consuming preparation of enzyme-conjugate and affinity probes. This method has promise for a variety of analytical applications. PMID:27108282

  10. On the organizing role of nonmuscular forces during performance of a giant circle in gymnastics.

    PubMed

    Sevrez, Violaine; Rao, Guillaume; Berton, Eric; Bootsma, Reinoud J

    2012-02-01

    Five elite gymnasts performed giant circles on the high bar under different conditions of loading (without and with 6-kg loads attached to the shoulders, waist or ankles). Comparing the gymnasts' kinematic pattern of movement with that of a triple-pendulum moving under the sole influence of nonmuscular forces revealed qualitative similarities, including the adoption of an arched position during the downswing and a piked position during the upswing. The structuring role of nonmuscular forces in the organization of movement was further reinforced by the results of an inverse dynamics analysis, assessing the contributions of gravitational, inertial and muscular components to the net joint torques. Adding loads at the level of the shoulders, waist or ankles systematically influenced movement kinematics and net joint torques. However, with the loads attached at the level of the shoulders or waist, the load-induced changes in gravitational and inertial torques provided the required increase in net joint torque, thereby allowing the muscular torques to remain unchanged. With the loads attached at the level of the ankles, this was no longer the case and the gymnasts increased the muscular torques at the shoulder and hip joints. Together, these results demonstrate that expert gymnasts skillfully exploit the operative nonmuscular forces, employing muscle force only in the capacity of complementary forces needed to perform the task. PMID:21975422

  11. Introspection, empathy, and the semi-circle of mental health.

    PubMed

    Kohut, H

    1982-01-01

    Written shortly before his death, Heinz Kohut's last paper opens with a discussion of the paper 'Introspection, empathy, and psychoanalysis', written in 1959, which he presented at the Twenty-fifth Anniversary Meeting of the Chicago Institute for Psychoanalysis. In his first essay on the role of empathy in psychoanalysis, an essay that according to Kohut provided a foundation for many of his subsequent investigations in the field of depth psychology, he advanced the thesis that the introspective-empathic stance of the observer defines the science of psychoanalysis. The author explains that he was moved to propose this operational definition of psychoanalysis twenty-five years before because he felt that the introduction of the psychobiological concept of the drives (as well as various social psychological concepts) had not led to a true integration of psychoanalysis with biology or medicine but to a psychological and moral view of 'Guilty Man' that worked to distort the analyst's perception in the clinical and applied field. Kohut asserts that by defining itself operationally, psychoanalysis can accept itself as psychology, a psychology that studies man in terms of a self attempting to realize the programme laid down in his depth during the span of his life. The final section of the paper is devoted to a re-examination of man's intergenerational relationships in light of the shift Kohut advocates from psychobiology to psychology. The Oedipus complex is not to be understood as the end product of the uninfluentiable conflict of basic opposing instincts but as the result of interferences that impinge on man's development. Acknowledging the mythic power of Freud's formulation of the Oedipus complex, the author offers a dose of mythical counter-magic (to which the 'semi-circle of mental health' in the paper's title refers) and a re-interpretation of the story of King Oedipus. Kohut believes that the essence of human experience is not to be found in the biologically

  12. Computer-assisted dissection of rolling circle DNA replication.

    PubMed

    Koonin, E V; Ilyina, T V

    1993-01-01

    A comparative analysis of the proteins involved in initiation and termination of rolling circle replication (RCR) was performed using computer-assisted methods of data based screening, motif search and multiple amino acid sequence alignment. Two vast classes of such proteins were delineated, one of these being associated with RCR proper, and the other with mobilization (conjugal transfer) of plasmid DNA. The common denominator of the two classes was found to be a conserved amino acid motif that consists of the sequence HisUHisUUU (U--bulky hydrophobic residue; hereafter HUH motif). Based on analogies with metalloenzymes, it is hypothesized that the two conserved His residues this motif may be involved in metal ion coordination required for the activity of the RCR and mobilization proteins. The proteins of the replication (Rep) class contained two additional conserved motifs, with the motif around the Tyr residue(s) forming the covalent link with nicked DNA being located C-proximally of the HUH motif. This class further split into two large superfamilies and several smaller families, with the proteins belonging to a single but not to different (super)families demonstrating statistically significant similarity to each other. Superfamily I, prototyped by the gene A proteins of small isometric single-stranded (ss) DNA bacteriophages, included also Rep proteins of P2-related double-stranded (ds) DNA bacteriophages, the small phage-plasmid hybrid phasyl, and several cyanobacterial and archaebacterial plasmids. These proteins contained two invariant Tyr residues separated by three partially conserved amino acids, suggesting that they all may share the cleavage-ligation mechanism proposed for phi X174 A protein and involving alternate covalent binding of both tyrosines to DNA (Van Mansfeld, A.D., Van Teeffelen, H.A., Baas, P.D., Jansz, H.S., 1986. Nucl. Acids Res. 14, 4229-4238). Superfamily II included Rep proteins of a number of ssDNA plasmids replicating mainly in gram

  13. Accurate episomal HIV 2-LTR circles quantification using optimized DNA isolation and droplet digital PCR

    PubMed Central

    Malatinkova, Eva; Kiselinova, Maja; Bonczkowski, Pawel; Trypsteen, Wim; Messiaen, Peter; Vermeire, Jolien; Verhasselt, Bruno; Vervisch, Karen; Vandekerckhove, Linos; De Spiegelaere, Ward

    2014-01-01

    Introduction In HIV-infected patients on combination antiretroviral therapy (cART), the detection of episomal HIV 2-LTR circles is a potential marker for ongoing viral replication. Quantification of 2-LTR circles is based on quantitative PCR or more recently on digital PCR assessment, but is hampered due to its low abundance. Sample pre-PCR processing is a critical step for 2-LTR circles quantification, which has not yet been sufficiently evaluated in patient derived samples. Materials and Methods We compared two sample processing procedures to more accurately quantify 2-LTR circles using droplet digital PCR (ddPCR). Episomal HIV 2-LTR circles were either isolated by genomic DNA isolation or by a modified plasmid DNA isolation, to separate the small episomal circular DNA from chromosomal DNA. This was performed in a dilution series of HIV-infected cells and HIV-1 infected patient derived samples (n=59). Samples for the plasmid DNA isolation method were spiked with an internal control plasmid. Results Genomic DNA isolation enables robust 2-LTR circles quantification. However, in the lower ranges of detection, PCR inhibition caused by high genomic DNA load substantially limits the amount of sample input and this impacts sensitivity and accuracy. Moreover, total genomic DNA isolation resulted in a lower recovery of 2-LTR templates per isolate, further reducing its sensitivity. The modified plasmid DNA isolation with a spiked reference for normalization was more accurate in these low ranges compared to genomic DNA isolation. A linear correlation of both methods was observed in the dilution series (R2=0.974) and in the patient derived samples with 2-LTR numbers above 10 copies per million peripheral blood mononuclear cells (PBMCs), (R2=0.671). Furthermore, Bland–Altman analysis revealed an average agreement between the methods within the 27 samples in which 2-LTR circles were detectable with both methods (bias: 0.3875±1.2657 log10). Conclusions 2-LTR circles

  14. Non-great-circle propagation modes on the high-latitude HF radio path

    NASA Astrophysics Data System (ADS)

    Blagoveshchensky, D. V.; Borisova, T. D.; Kalishin, A. S.

    2009-04-01

    We consider characteristics of the non-great-circle signals on the Murmansk—St. Petersburg oblique sounding path with a distance of 1050 km. The path crosses the main ionospheric trough and is highly influenced by the trough’s polar wall and the boundary of diffuse precipitations. Field-aligned ionospheric irregularities and ionization gradients are often observed in this area. The data analysis was performed for quiet, moderately disturbed, and strongly disturbed conditions and for different local times. The main results are as follows. Non-great-circle signals in the form of scattered waves mostly occur in the nighttime hours. The nighttime non-great-circle signals always appear under both quiet and disturbed conditions, while the signals reflected from the ionization gradients appear at any local time during the disturbed periods (storms, substorms). Non-great-circle signals with intense reflections from the ionization gradients are most often observed during a moderate disturbance, especially in the nighttime hours. The ray-tracing model of non-great-circle propagation shows that the calculated oblique sounding ionograms generally coincide with the experimental ones.

  15. Human Immunodeficiency Virus Type 1 Two-Long Terminal Repeat Circles: A Subject for Debate.

    PubMed

    Olivares, Isabel; Pernas, María; Casado, Concepción; López-Galindez, Cecilio

    2016-01-01

    HIV-1 infections are characterized by the integration of the reverse transcribed genomic RNA into the host chromosomes making up the provirus. In addition to the integrated proviral DNA, there are other forms of linear and circular unintegrated viral DNA in HIV-1-infected cells. One of these forms, known as two-long terminal repeat circles, has been extensively studied and characterized both in in vitro infected cells and in cells from patients. Detection of two-long terminal repeat circles has been proposed as a marker of antire-troviral treatment efficacy or ongoing replication in patients with undetectable viral load. But not all authors agree with this use because of the uncertainty about the lifespan of the two-long terminal repeat circles. We review the major studies estimating the half-life of the two-long terminal repeat circles as well as those proposing its detection as a marker of ongoing replication or therapeutic efficacy. We also review the characteristic of these circular forms and the difficulties in its detection and quantification. The variety of approaches and methods used in the two-long terminal repeat quantification as well as the low reliability of some methods make the comparison between results difficult. We conclude that it is not possible to draw a clear supposition about the lifespan of two-long terminal repeat circles and consequently they should not be used as a marker of ongoing replication without a careful analysis of the methods and results. PMID:26936759

  16. In vitro replication of mitochondrial plasmid mp1 from the higher plant Chenopodium album (L.): a remnant of bacterial rolling circle and conjugative plasmids?

    PubMed

    Backert, S; Kunnimalaiyaan, M; Börner, T; Nielsen, B L

    1998-12-11

    According to the endosymbiotic theory, mitochondrial genomes evolved from the chromosome of an alpha-proteobacterium-like ancestor and developed during evolution an extraordinary variation in size, structure and replication. We studied in vitro DNA replication of the mitochondrial circular plasmid mp1 (1309 bp) from the higher plant Chenopodium album (L.) as a model system that replicates in a manner reminiscent of bacterial rolling circle plasmids. Several mp1 subclones were tested for their ability to support DNA replication using a newly developed in vitro system. Neutral/neutral two-dimensional gel electrophoresis of the in vitro products revealed typical simple Y patterns of intermediates consistent with a rolling circle type of replication. Replication activity was very high for a BamHI-restricted total plasmid DNA clone, a 464 bp BamHI/KpnI fragment and a 363 bp BamHI/SmaI fragment. Further subcloning of a 148 bp BamHI/EcoRI fragment resulted in the strongest in vitro DNA replication activity, while a 1161 bp-template outside of this region resulted in a substantial loss of activity. Electron microscopic studies of in vitro DNA replication products from the highly active clones also revealed sigma-shaped molecules. These results support our in vivo data for the presence of a predominant replication origin between positions 628 and 776 on the plasmid map. This sequence shares homology with double-stranded rolling circle origin (dso) or transfer origin (oriT) nicking motifs from bacterial plasmids. mp1 is the first described rolling circle plasmid in eukaryotes. PMID:9837722

  17. Women and Chemistry in Regency England: New Light on the Marcet Circle.

    PubMed

    Leigh, G Jeffery; Rocke, Alan J

    2016-02-01

    Jane Marcet's Conversations on Chemistry (first edition, 1806) was possibly the best-selling English-language chemistry book of the first half of the nineteenth century. Recent scholarship has explored the degree to which her husband assisted in the writing of the book, without diminishing the high merits of the author. Previously unpublished correspondence, some of which appears here for the first time, casts new light on the social and professional circle of Jane and Alexander Marcet, including its influence on Jane's book. One of the members of that circle was a hitherto unrecognised but highly capable young female chemist, Frederica Sebright. The story told here underlines the tensions in elite circles in early nineteenth-century England between broad-minded acceptance and patronising limitations for women in science. PMID:27315052

  18. Great circle solution to polarization-based quantum communication (QC) in optical fiber

    DOEpatents

    Nordholt, Jane Elizabeth; Peterson, Charles Glen; Newell, Raymond Thorson; Hughes, Richard John

    2016-03-15

    Birefringence in optical fibers is compensated by applying polarization modulation at a receiver. Polarization modulation is applied so that a transmitted optical signal has states of polarization (SOPs) that are equally spaced on the Poincare sphere. Fiber birefringence encountered in propagation between a transmitter and a receiver rotates the great circle on the Poincare sphere that represents the polarization bases used for modulation. By adjusting received polarizations, polarization components of the received optical signal can be directed to corresponding detectors for decoding, regardless of the magnitude and orientation of the fiber birefringence. A transmitter can be configured to transmit in conjugate polarization bases whose SOPs can be represented as equidistant points on a great circle so that the received SOPs are mapped to equidistant points on a great circle and routed to corresponding detectors.

  19. Formula for the rms blur circle radius of Wolter telescope based on aberration theory

    NASA Technical Reports Server (NTRS)

    Shealy, David L.; Saha, Timo T.

    1990-01-01

    A formula for the rms blur circle for Wolter telescopes has been derived using the transverse ray aberration expressions of Saha (1985), Saha (1984), and Saha (1986). The resulting formula for the rms blur circle radius over an image plane and a formula for the surface of best focus based on third-, fifth-, and seventh-order aberration theory predict results in good agreement with exact ray tracing. It has also been shown that one of the two terms in the empirical formula of VanSpeybroeck and Chase (1972), for the rms blur circle radius of a Wolter I telescope can be justified by the aberration theory results. Numerical results are given comparing the rms blur radius and the surface of best focus vs the half-field angle computed by skew ray tracing and from analytical formulas for grazing incidence Wolter I-II telescopes and a normal incidence Cassegrain telescope.

  20. Mosh pits and Circle pits: Collective motion at heavy metal concerts

    NASA Astrophysics Data System (ADS)

    Bierbaum, Matthew; Silverberg, Jesse L.; Sethna, James P.; Cohen, Itai

    2013-03-01

    Heavy metal concerts present an extreme environment in which large crowds (~102 -105) of humans experience very loud music (~ 130 dB) in sync with bright, flashing lights, often while intoxicated. In this setting, we find two types of collective motion: mosh pits, in which participants collide with each other randomly in a manner resembling an ideal gas, and circle pits, in which participants run collectively in a circle forming a vortex of people. We model these two collective behaviors using a flocking model and find qualitative and quantitative agreement with the behaviors found in videos of metal concerts. Futhermore, we find a phase diagram showing the transition from a mosh pit to a circle pit as well as a predicted third phase, lane formation.

  1. Botanical prospecting for uranium in the Circle Cliffs area, Garfield County, Utah

    USGS Publications Warehouse

    Kleinhampl, F.J.; Koteff, Carl

    1956-01-01

    Astragalus pattersoni and Stanleya pinnata broadly define some uraniferous localities adjacent to the contact of the Moenkopi formation and the Shinarump member of the Chinle formation, but the general paucity of Astragalus in the Circle Cliffs area limits the usefulness of this genus. Astragalus pattersoni, Stanleya pinnata, and Aster venustus(?) may serve as guides to mineralized parts of the Salt Wash sandstone member of the Morrison formation in the Circle Cliffs area. Thick and thin sandstones of the Shinarump member generally can be distinguished by pinyon-juniper ration studies. These studies may supplement drilling to define channel-fill sandstones which are associated with ore deposits in the Circle Cliffs area. Ratio studies appear to be applicable to other areas throughout the Colorado Plateau where similar geological and ecological conditions exist.

  2. An analysis of two classes of grazing incidence mirrors for use with Rowland circle spectrometers

    NASA Astrophysics Data System (ADS)

    Green, James; Bowyer, Stuart

    1986-01-01

    Results are presented of a comparative analysis of Hettrick Bowyer Type II (HBII) and Wolter-Schwarzschild Type II (WSII) optics for use with Rowland circle spectrometers. The HBII can substitute, with few exceptions, for a WSII in any Rowland circle with little change in spectrometer performance or design. However, the HBII telescope offers several clear advantages over the WSII in these configurations. Because the HBII employs a virtual focus, it requires a much shorter instrument length than a WSII. For example, a 3-m Rowland circle spectrometer, fed by an optimized, f/10, 1-m diameter WSII, has a total instrument length of 6 m. If a HBII is used to feed the identical spectrometer, the entire instrument length can be as little as 3 m. In addition, the improved imaging gained with the larger graze angles of the HBII design results in better resolution in slitless operation modes.

  3. Traffic flow behavior at a single lane roundabout as compared to traffic circle

    NASA Astrophysics Data System (ADS)

    Lakouari, N.; Ez-Zahraouy, H.; Benyoussef, A.

    2014-09-01

    In this paper, we propose a stochastic Cellular Automata (CA) model to study traffic flow at a single-lane urban roundabout (resp. traffic circle) of N entry points (resp. exit points), the entry points are controlled by rates α1 and α2 while the removal rates from the exit points are denoted by β. The traffic is controlled by a self-organized scheme. Based on computer simulation, density profiles, global density and current are calculated in terms of rates. Furthermore, the phase diagrams for roundabout as well as traffic circle are constructed. It has turned out that the phase diagrams consist essentially of two phases namely free flow and jamming. It is noted that the typology of the phase diagrams of the roundabout is not similar to it in the traffic circle. Furthermore, we have compared the performance of the two systems in terms of the geometrical properties and the number of entry points.

  4. A SEARCH FOR CONCENTRIC CIRCLES IN THE 7 YEAR WILKINSON MICROWAVE ANISOTROPY PROBE TEMPERATURE SKY MAPS

    SciTech Connect

    Wehus, I. K.; Eriksen, H. K.

    2011-06-01

    In this Letter, we search for concentric circles with low variance in cosmic microwave background sky maps. The detection of such circles would hint at new physics beyond the current cosmological concordance model, which states that the universe is isotropic and homogeneous, and filled with Gaussian fluctuations. We first describe a set of methods designed to detect such circles, based on matched filters and {chi}{sup 2} statistics, and then apply these methods to the best current publicly available data, the 7 year Wilkinson Microwave Anisotropy Probe (WMAP) temperature sky maps. We compare the observations with an ensemble of 1000 Gaussian {Lambda}CDM simulations. Based on these tests, we conclude that the WMAP sky maps are fully compatible with the Gaussian and isotropic hypothesis as measured by low-variance ring statistics.

  5. Hydraulic characteristics of an underdrained irrigation circle, Muskegon County wastewater disposal system, Michigan

    USGS Publications Warehouse

    McDonald, M.G.

    1980-01-01

    Muskegon County, Mich., disposes of wastewater by spray irrigating farmland on its waste-disposal site. Buried drains in the highly permeable unconfined aquifer at the site control the level of the water table. Hydraulic conductivity of the aquifer and drain leakance, the reciprocal of resistance to flow into the drains, was determined at a representative irrigation circle while calibrating a model of the ground-water flow system. Hydraulic conductivity is .00055 meter per second, in the north zone of the circle, and .00039 meter per second in the south zone. Drain leakance is low in both zones: 0.0000029 meter per second in the north and 0.0000095 meter per second in the south. Low drain leakance is responsible for waterlogging when irrigation rates are maintained at design levels. The capacity of the study circle to accept wastewater has been reduced by more than 35%. (USGS)

  6. "Socratic Circles are a Luxury": Exploring the Conceptualization of a Dialogic Tool in Three Science Classrooms

    NASA Astrophysics Data System (ADS)

    Copelin, Michelle Renee

    Research has shown that dialogic instruction promotes learning in students. Secondary science has traditionally been taught from an authoritative stance, reinforced in recent years by testing policies requiring coverage. Socratic Circles are a framework for student-led dialogic discourse, which have been successfully used in English language arts and social studies classrooms. The purpose of this research was to explore the implementation process of Socratic Circles in secondary science classes where they have been perceived to be more difficult. Focusing on two physical science classes and one chemistry class, this study described the nature and characteristics of Socratic Circles, teachers' dispositions toward dialogic instruction, the nature and characteristics of student discussion, and student motivation. Socratic Circles were found to be a dialogic support that influenced classroom climate, social skills, content connections, and student participation. Teachers experienced conflict between using traditional test driven scripted teaching, and exploring innovation through dialogic instruction. Students experienced opportunities for peer interaction, participation, and deeper discussions in a framework designed to improve dialogic skills. Students in two of the classrooms showed evidence of motivation for engaging in peer-led discussion, and students in one class did not. The class that did not show evidence of motivation had not been given the same scaffolding as the other two classes. Two physical science teachers and one chemistry teacher found that Socratic Circles required more scaffolding than was indicated by their peers in other disciplines such as English and social studies. The teachers felt that student's general lack of background knowledge for any given topic in physical science or chemistry necessitated the building of a knowledge platform before work on a discussion could begin. All three of the teachers indicated that Socratic Circles were a

  7. VizieR Online Data Catalog: W1J00 and W2J00 Transit Circle Catalogs (Rafferty+, 2016)

    NASA Astrophysics Data System (ADS)

    Rafferty, T. J.; Holdenried, E. R.; Urban, S. E.

    2016-06-01

    The W1J00, named because it was the first (of two) Washington transit circle catalog to be referred to the Equinox of J2000.0, is the result of observations made with the Six-inch Transit Circle in Washington, D.C., between September 1977 and July 1982. The observing program was structured to be absolute, in the sense that the positions were not explicitly relying on any previous observations. The absolute positions were defined with respect to an internally consistent frame that was unique to the particular instrument. Following the reductions, comparisons with stars from the Hipparcos Catalogue (European Space Agency 1997) revealed unaccounted for systematic differences on the level of 100-200mas. It was decided, therefore, to include data on both the absolute positions reduced in way common to many past Washington transit circle catalogs, as well as the positions differentially adjusted to the system of the Hipparcos Catalog. The W1J00 contains mean positions of 7267 stars and 4383 observations of solar system objects. The majority of the stars fall into two categories; those from the Fifth Fundamental Catalog (FK5; Fricke et al 1988), and those from the Catalog Of 3539 Zodiacal Stars For The Equinox 1950.0 (Robertson 1940). The solar system objects include the Sun, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, eight minor planets (Eunomia, Flora, Hebe, Iris, Juno, Metis, Pallas, and Vesta), and the dwarf planet Ceres. Characteristics of the W1J00 catalog: Category Range Average ------------------------------------------------------------- Magnitudes -1.6 to 10.4 7.18 RA standard errors of the mean 15 to 460 mas 98 mas Dec standard errors of the mean 10 to 400 mas 107 mas RA Number of observations / star 3 to 187 10 Dec Number of observations / star 2 to 179 10 Declination coverage -39 to +90 degrees ------------------------------------------------------------- Details of the W1J00 can be found in Rafferty, Holdenried, and Urban (2016, Publ. USNO, 2nd

  8. Separability and entanglement in C{sup 2}(multiply-in-circle sign)C{sup 3}(multiply-in-circle sign)C{sup N} composite quantum systems

    SciTech Connect

    Fei, Shao-Ming; Gao, Xiu-Hong; Wang, Xiao-Hong; Wang, Zhi-Xi; Wu, Ke

    2003-08-01

    The separability and entanglement of quantum mixed states in C{sup 2}(multiply-in-circle sign)C{sup 3}(multiply-in-circle sign)C{sup N} composite quantum systems are investigated. It is shown that all quantum states {rho} with positive partial transposes and rank r({rho}){<=}N are separable.

  9. Expanding the Circle: Respecting the Past Preparing for the Future.

    ERIC Educational Resources Information Center

    Ness, Jean E.; Huisken, Jennifer S.

    This curriculum was developed to support American Indian high school students in their transition from high school to postsecondary life. It provides a structured process and culturally relevant activities that can be led by either teachers, tribal elders, community members, or paraprofessionals. The curriculum is based on principles such as a…

  10. A Study of Traditional Circle Games of Five-Year-Old United States Public School Kindergarten Children.

    ERIC Educational Resources Information Center

    Rothlein, Liz; Einspruch, Eric

    A total of 203 teachers of 5-year-olds in public school kindergartens representing 35 states responded to a questionnaire about traditional circle games. The teachers were asked to identify three of the favorite traditional circle games used in their classrooms and to indicate how often and how long the games were played. In addition, teachers…

  11. Circle Time in Pre-School. Reprints and Miniprints from Department of Educational and Psychological Research. No. 785.

    ERIC Educational Resources Information Center

    Reich, Lena Rubinstein

    A study examined the curricular event in Swedish preschools known as "circle time," a daily event in most schools during which children, teachers, and sometimes parents gather in a circle for 20-30 minutes and share songs, discussion, music, storytelling, and group play. A special theme, such as the environment or a holiday, may also be dealt with…

  12. Circle chain embracing donor-acceptor organic dye: simultaneous improvement of photocurrent and photovoltage for dye-sensitized solar cells.

    PubMed

    Liu, Jian; Numata, Youhei; Qin, Chuanjiang; Islam, Ashraful; Yang, Xudong; Han, Liyuan

    2013-09-01

    We demonstrate for the first time that employing a circle chain embracing π-conjugated backbone is a promising strategy to construct superior organic sensitizers for dye-sensitized solar cells (DSCs), with simultaneous improvement of photocurrent and photovoltage. A DSC based on one circle chain embracing dye produced a high conversion efficiency of 8.34%. PMID:23604204

  13. Bifurcation structure of successive torus doubling

    NASA Astrophysics Data System (ADS)

    Sekikawa, Munehisa; Inaba, Naohiko; Yoshinaga, Tetsuya; Tsubouchi, Takashi

    2006-01-01

    The authors discuss the “embryology” of successive torus doubling via the bifurcation theory, and assert that the coupled map of a logistic map and a circle map has a structure capable of generating infinite number of torus doublings.

  14. Throwing a Better Party: Local Mobilizing Institutions and the Youth Vote. CIRCLE Working Paper 13.

    ERIC Educational Resources Information Center

    Shea, Daniel M.

    2004-01-01

    A shrinking number of Americans are interested in politics?a trend pronounced among younger citizens. Politicians, academics, civic leaders and others are scrambling to find solutions. This study was commissioned by the Center for Information and Research on Civic Learning and Engagement (CIRCLE) and focuses on local political parties.…

  15. Education, Enlightenment and Positivism: The Vienna Circle's Scientific World-Conception Revisited

    ERIC Educational Resources Information Center

    Uebel, Thomas E.

    2004-01-01

    The scientific world-conception is properly understood as an enlightenment philosophy only if the current reassessment of the historical Vienna Circle(as opposed to the caricature still prevalent in the popular philosophical imagination) is once more extended to comprehend not only its thorough-going epistemological anti-foundationalism, but also…

  16. Themes Emphasized in Social Studies and Civics Classes: New Evidence. CIRCLE Fact Sheet.

    ERIC Educational Resources Information Center

    Levine, Peter; Lopez, Mark Hugo

    2004-01-01

    A survey conducted by the Council for Excellence in Government and The Center for Information & Research on Civic Learning & Engagement (CIRCLE) reveals unprecedented information about the content and significance of civics and social studies classes today. Overall, the curriculum and message of history and social studies classes appear to be more…

  17. An Investigation of "Circle of Friends" Peer-Mediated Intervention for Students with Autism

    ERIC Educational Resources Information Center

    Schlieder, Mary; Maldonado, Nancy; Baltes, Beate

    2014-01-01

    The dramatic rise in children diagnosed with autism spectrum disorder (ASD) is accompanied by a substantial increase in public school inclusion. A growing body of research supports the need for teachers proficient in evidence-based practices to support such students. One strategy involves using peer support networks like Circle of Friends (CoF)…

  18. A Refinement of Collaborative Circles Theory: Resource Mobilization and Innovation in an Emerging Sport

    ERIC Educational Resources Information Center

    Corte, Ugo

    2013-01-01

    Farrell's (2001) theory of collaborative circles provides a useful frame for analyzing the interpersonal dynamics that enable creative collaboration in small groups, but it leaves contextual factors of collaboration undertheorized. Using ethnographic data on freestyle BMXers in Greenville, North Carolina, this article demonstrates how resource…

  19. Student Facilitation and Predictors of Engagement in Peer-Led Literature Circle Discussions

    ERIC Educational Resources Information Center

    Young, Chase

    2012-01-01

    The purpose of this research was to examine the relation between students' personality traits and the extent of their engagement and facilitation in peer-led literature circle discussions. The research was guided by two questions. To what extent do reading ability, gender, and personality traits predict the quality of verbal engagement in…

  20. Using Literature Circles to Increase Reading Comprehension in Third Grade Elementary Students

    ERIC Educational Resources Information Center

    Briggs, Shawna R.

    2010-01-01

    Reading comprehension strategies are important skills for a child to learn. Good strategies support struggling students to be more successful in all subjects at school as reading is the basis for subsequent mastery of most subjects (Bender & Larkin, 2003). This action research project examined the use of literature circles in a third grade class.…

  1. Motivating Women Offenders through Process-Based Writing in a Literacy Learning Circle.

    ERIC Educational Resources Information Center

    Stino, Zandra H.; Palmer, Barbara C.

    1999-01-01

    Finds that a participatory literacy learning circle employing process-based writing activities significantly improved both writing skills and self esteem of a group of women at a residential treatment center who had received court sentences for drug sales or alcohol abuse. (SR)

  2. Effect of hybrid circle reservoir injected with wavelet-neurons on performance of echo state network.

    PubMed

    Cui, Hongyan; Feng, Chen; Chai, Yuan; Liu, Ren Ping; Liu, Yunjie

    2014-09-01

    The Echo State Network (ESN) has attracted wide attention for its superior performance in chaos time-series prediction. However, the complicated ESN topologies and the random reservoirs are difficult to implement in practice. We propose a hybrid circle reservoir (HCR) ESN architecture that comprises the following features: (1) built with low complexity circle reservoir; (2) partly injected with wavelet-neurons; (3) uses fixed connection weights in both input matrix and dynamic reservoir matrix. The HCR model has been successfully applied to solve six application problems, and the results are used to compare with the existing low complexity simple circle reservoir (SCR) ESN. Furthermore, we analyze the performance of the new model under different ratios of wavelet-neurons, different circle distributions and different input sign patterns. Simulation results show that the HCR model achieves significantly better performance in prediction accuracy than the SCR model. Additionally, the HCR model has similar low complexity as the SCR. Moreover, the short-term memory capacity (MC) in the HCR is close to the theoretical optimal MC value. PMID:24997457

  3. Cultural Safety Circles and Indigenous Peoples' Perspectives: Inclusive Practices for Participation in Higher Education

    ERIC Educational Resources Information Center

    Aseron, Johnnie; Greymorning, S. Neyooxet; Miller, Adrian; Wilde, Simon

    2013-01-01

    Indigenous experiences, as found within traditional ways and cultural practices, are an acknowledgement of traditional methods for sharing, learning, and collective knowledge development and maintenance. The application of Cultural Safety Circles can help provide a collective space where definitions for cultural and educational exchange can take…

  4. Biophysical and chemical handles to control the size of DNA nanoparticles produced by rolling circle amplification.

    PubMed

    Lee, So Yeon; Kim, Kyoung-Ran; Bang, Duhee; Bae, Se Won; Kim, Hak Joong; Ahn, Dae-Ro

    2016-08-16

    Although rolling circle amplification (RCA) is an efficient method to produce DNA materials for biomedical applications, it does not yield nano-sized products suitable for intracellular delivery. We here provide the ways to control the size of RCA products and show a potential application of the size-controlled DNA nanoparticles. PMID:27464359

  5. The Listening Circle: Using the SBI Model to Enhance Peer Feedback

    ERIC Educational Resources Information Center

    Bommelje, Rick

    2012-01-01

    The Listening Circle is a learning activity that is designed to provide students with the opportunity to connect listening knowledge with observed behaviors and to strengthen student peer feedback. Not knowing how to give feedback can result in messages that are confusing, tactless, and counter-productive. Many feedback messages leave the receiver…

  6. Circle Justice: A Creative Arts Approach to Conflict Resolution in the Classroom

    ERIC Educational Resources Information Center

    Gibbons, Karen

    2010-01-01

    This brief report describes a cooperative classroom art therapy intervention in a public elementary school that provided conflict resolution education, social learning, and group cohesion among sixth-grade students. The organizing framework of a "circle justice" group explored the roles of fictional characters in conflict, including group…

  7. Teacher Perceptions of the Use of Literature Circles and Student Engagement in Reading

    ERIC Educational Resources Information Center

    Maraccini, Barbara Jerri

    2011-01-01

    The purpose of this study was to examine teachers' perceptions of commonly used instructional practices in reading, the use of literature circles, and student engagement at the middle school level. This study used a survey of teachers to collect data and the study design included descriptive and comparative components. It was descriptive in…

  8. Promoting Social Competence in School-Aged Children: The Effects of the Open Circle Program

    ERIC Educational Resources Information Center

    Hennessey, Beth A.

    2007-01-01

    One hundred fifty-four fourth graders took part in an investigation of the Open Circle Program (OCP), an intervention model that encourages students, teachers and administrators to learn and practice communication, self-control and social problem-solving skills. Eight classrooms, two in each of four schools, were sampled. Two of these schools were…

  9. Using Social Networks and ICTs to Enhance Literature Circles: A Practical Approach

    ERIC Educational Resources Information Center

    Walker, Andrea

    2010-01-01

    The purpose of this paper is to describe and demonstrate how social networks such as "Facebook" and "Goodreads", and information and communication technologies (ICTs) tools like laptops and iPods can support and enhance literature circles. The innovation described is implemented by the library and aims to promote reading for all students…

  10. Constructing Knowledge about the Trigonometric Functions and Their Geometric Meaning on the Unit Circle

    ERIC Educational Resources Information Center

    Altman, Renana; Kidron, Ivy

    2016-01-01

    Processes of knowledge construction are investigated. A learner is constructing knowledge about the trigonometric functions and their geometric meaning on the unit circle. The analysis is based on the dynamically nested epistemic action model for abstraction in context. Different tasks are offered to the learner. In his effort to perform the…

  11. Functions of Rep and Rep' during porcine circovirus rolling-circle replication

    Technology Transfer Automated Retrieval System (TEKTRAN)

    PCV replicates its single-stranded (ss) DNA genome via the rolling-circle replication (RCR) mechanism. In contrast to other RCR biological systems which utilize only one multi-functional protein (Rep) to replicate their respective genomes, PCV requires two proteins (Rep and Rep'). Rep and Rep' are i...

  12. Using Reading Circles Strategy for Developing Preparatory Students' Critical Reading Skills and Social Skills

    ERIC Educational Resources Information Center

    Abdelrasoul, Mohamed Mahmoud Ibrahim

    2014-01-01

    The present study aimed at developing the necessary critical reading skills and social skills of the Egyptian EFL second year preparatory school students, through a proposed program based on using reading circles strategy. The study participants were 44 students from Sohag Experimental Preparatory School in Sohag Governorate. Instruments of the…

  13. Runaway Climate Change as Challenge to the "Closing Circle" of Education for Sustainable Development

    ERIC Educational Resources Information Center

    Selby, David; Kagawa, Fumiyo

    2010-01-01

    Education for sustainable development (ESD) is the latest and thickest manifestation of the "closing circle" of policy-driven environmental education. Characterised by definitional haziness, a tendency to blur rather than lay bare inconsistencies and incompatibilities, and a cozy but ill-considered association with the globalisation agenda, the…

  14. Some Comments On: A Historical Note on the Proof of the Area of a Circle

    ERIC Educational Resources Information Center

    Naidu, Jaideep T.; Sanford, John F.

    2011-01-01

    In a recent paper by Wilamowsky et al. [6], an intuitive proof of the area of the circle dating back to the twelfth century was presented. They discuss challenges made to this proof and offer simple rebuttals to these challenges. The alternative solution presented by them is simple and elegant and can be explained rather easily to non-mathematics…

  15. Dinner Tables and Concentric Circles: A Harmony of Mathematics, Music, and Physics

    ERIC Educational Resources Information Center

    Douthett, Jack; Krantz, Richard J.

    2008-01-01

    How should men and women be seated around a dinner table to maximize conversation between members of the opposite sex? What can be said about the distribution of points around two concentric circles? How are the white and black keys on the piano keyboard organized? What spin configuration in the Ising model minimizes energy? These four problems…

  16. Training the Scientific Thinking Circle in Pre- and Primary School Children

    ERIC Educational Resources Information Center

    Dejonckheere, Peter J. N.; Van De Keere, Kristof; Mestdagh, Nele

    2009-01-01

    Using two experiments, the authors examined the extent to which the scientific thinking circle can be used as heuristics to support scientific thinking in a classroom of children between the ages of 3 and 9 years old. To do this, the authors asked the children to build a bridge, raft, or electrical circuit using the material available to them.…

  17. The tentative exploration of Shen Kuo's circle method and proper method

    NASA Astrophysics Data System (ADS)

    Guo, Shengchi

    In this paper, the circle method and proper method established by Shen Kuo, a famous scientist of Northern Song Dynasty, are discussed tentatively. This is a new approach for calculating the position of the sun on the ecliptic. The velocity of sun's annual apparent motion is regarded as the sum of a constant and a variation.

  18. Determination of positions of solar system bodies at Repsold meridian circle from 1992 till 1999

    NASA Astrophysics Data System (ADS)

    Maigurova, N. V.; Pogoniy, A. D.; Pyshnenko, V. N.; Sibilev, V. P.

    2002-04-01

    Position of the Solar system bodies: Uran, Neptune, Galilean satellites of Jupiter, satellite of Saturn Titan, Ceres, Pallas, Juno, Vesta, Hebe, Iris, and Melpomene were obtained from observations at Repsold Meridian Circle of Nikolaev Astronomical Observatory made in 1992-1999.

  19. Math Circles: A Tool for Promoting Engagement among Middle School Minority Males

    ERIC Educational Resources Information Center

    Kennedy, Eugene; Smolinsky, Lawrence

    2016-01-01

    This article presents results of a case study of a math circle designed for low income, minority students from an inner city middle school. The students were 6th, 7th and 8th grade African American and Hispanic males enrolled in a science, technology, engineering and mathematics focused charter school. The study focused on the impact of…

  20. "Slow Down, You Move Too Fast:" Literature Circles as Reflective Practice

    ERIC Educational Resources Information Center

    Sanacore, Joseph

    2013-01-01

    Becoming an effective literacy learner requires a bit of slowing down and appreciating the reflective nature of reading and writing. Literature circles support this instructional direction because they provide opportunities for immersing students in discussions that encourage their personal responses. When students feel their personal responses…

  1. Talking Books: Gender and the Responses of Adolescents in Literature Circles

    ERIC Educational Resources Information Center

    Lloyd, Rachel Malchow

    2006-01-01

    The use of student-led discussions, or literature circles, offers the potential to engage all students through a more democratic, dialogic approach. The central goal of this research was to understand how adolescents practise literacy within the context of a peer reading group, and how gender impacts these practices. Transcripts of student-led…

  2. Facebook and Virtual Literature Circle Partnership in Building a Community of Readers

    ERIC Educational Resources Information Center

    Stewart, Paulette

    2009-01-01

    Social networks have given rise to a reading activity called an online literature circle. Generally from four to six students meet together in an online chat room to discuss the same reading. In this environment students engage in critical thinking and reflection as they read, discuss and respond to books. Collaboration is at the heart of this…

  3. Encounters with Wisdom: A Case Study of Community Worker Reflection Circles in San Antonio, TX

    ERIC Educational Resources Information Center

    Arispe, Don D.

    2013-01-01

    This case study focuses upon the transformational experiences of 28 social service and pastoral workers engaged in a Reflection Circle Process (RCP) in San Antonio, TX. The RCP involves the writing of a holistic journal entry, known as a process note, coupled with an in-depth exploration of the note with the help of a group of trusted peers, known…

  4. A Study of Traditional Circle Games Played in Public School Kindergartens across the United States.

    ERIC Educational Resources Information Center

    Rothlein, Liz; And Others

    1988-01-01

    Investigates traditional circle games played in 203 public school kindergartens in 35 states. Results indicate that music/movement and racing games were the major game categories; the most common frequency and duration was three times per week for 20 minutes; and the purposes of the games were to have fun, and to foster social, physical motor, and…

  5. Dialing in to a Circle of Trust: A "Medium" Tech Experiment and Poetic Evaluation

    ERIC Educational Resources Information Center

    Love, Christine T.

    2012-01-01

    In his 2004 book "A Hidden Wholeness," Parker Palmer makes explicit the unique qualities of the transformational "circle of trust." He describes a group of people embracing the paradox of "being alone together," where the only goal of the group is to invite the emergence of the soul of each individual, through journaling and carefully constructed…

  6. Virtual Learning Circles: Utilizing Online Message Board Interactions for Strengthening Literacy Development.

    ERIC Educational Resources Information Center

    Thomas, Matt; Hofmeister, David

    Educators need to better understand how Internet discussion boards can be used in their classrooms. The process of trying to learn more about potential efficacy of a merger of two potent education tools (Learning or Literature Circles and online discussion boards) is currently underway. A large research study has been designed to examine the…

  7. Quality Circles. ERIC Highlights for School Administrators, May/June 1983.

    ERIC Educational Resources Information Center

    Lake, Sara

    Developed by Japanese corporations to improve productivity and product quality, quality circles (QC's) are small, voluntary groups of workers who share common job responsibilities and who meet regularly to generate solutions to problems. Features of QC's that are applicable to schools are examined in the nine articles summarized in this annotated…

  8. Literature Circles: Meeting Reading Standards, Making Personal Connections, and Appreciating Other Interpretations

    ERIC Educational Resources Information Center

    Latendresse, Carter

    2004-01-01

    This article discusses a reading instruction applicable to widely diverse classrooms, because it weaves together dynamic strands from three approaches to teaching reading: literature circle method, reciprocal teaching, and modern literary theories. The author presents three stages to achieve reading success: (1) applying the key features of…

  9. A Cost-Benefit Analysis of Hollow Water's Community Holistic Circle Healing Process.

    ERIC Educational Resources Information Center

    Couture, Joe; Parker, Ted; Couture, Ruth; Laboucane, Patti

    Four Native American communities in Manitoba (Canada) known as Hollow Water devised a healing system for sexual abuse--the Hollow Water First Nation Community Holistic Circle Healing (CHCH). While integrating elements of a number of federal and provincially funded services, the 13-step CHCH healing process is based on the seven Midewin teachings…

  10. Dear Nel: Opening the Circles of Care (Letters to Nel Noddings)

    ERIC Educational Resources Information Center

    Lake, Robert

    2012-01-01

    This collection is a moving tribute to Nel Noddings, a fascinating and influential scholar who has contributed greatly to numerous fields, including education, feminism, ethics, and the study of social justice and equity. "Dear Nel: Opening the Circles of Care" presents contributions from renowned teachers, educators, and activists, such as David…

  11. 78 FR 9910 - Circle Environmental #1 and #2 Sites; Dawson, Terrell County, GA; Notice of Settlement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-12

    ...Under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), the United States Environmental Protection Agency has entered into a settlement with thirty-four (34) parties to recover past cost resulting from a removal action at the Circle Environmental 1 and 2 Superfund Sites located in Dawson, Terrell County,...

  12. 78 FR 44119 - Circle Environmental #1 Superfund Site; Dawson, Terrell County, Georgia; Notice of Settlement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-23

    ...Under 122(h) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), the United States Environmental Protection Agency has entered into a settlement with Walter G. Mercer, Jr. concerning the Circle Environmental 1 Superfund Site located in Dawson, Terrell County, Georgia. The settlement addresses cost incurred by the agency in conducting a fund lead......

  13. Measuring the Impact of the Circle of Trust[R] Approach

    ERIC Educational Resources Information Center

    Smith, Janet

    2012-01-01

    Since the first Circle of Trust retreat was offered in 2005, the Center for Courage & Renewal (CCR) and other individual facilitators across the United States, Canada, and Australia have continued to offer many cross-professional retreats, as they have proven extremely popular. They are designed for people from any profession who want to deepen…

  14. Strategic Framing Study Circles: Toward a Gold Standard of Framing Pedagogy

    ERIC Educational Resources Information Center

    Feinberg, Jane

    2009-01-01

    This article explains how communities of practice have been developed as part of FrameWorks' field-building efforts. Strategic Framing Study Circles, as they are known, have been conducted with four statewide coalitions, one group of national organizations, and an emerging regional coalition. The goal of each community of practice is to build…

  15. Evaluating Quality Circles in a College of Further Education. Manchester Monographs 31.

    ERIC Educational Resources Information Center

    Atkinson, Tim

    Quality circles (QCs) are small volunteer groups of workers who meet weekly with a trained leader operating to a strict code of conduct. They use techniques of brainstorming, cause and effect classification, pareto analysis, and presentation to consider work-related problems and recommend solutions to management. QCs have been tried in educational…

  16. Circle of Life HIV/AIDS-Prevention Intervention for American Indian and Alaska Native Youth

    ERIC Educational Resources Information Center

    Kaufman, Carol E.; Litchfield, Anne; Schupman, Edwin; Mitchell, Christina M.

    2012-01-01

    This article describes the objectives, theoretical bases, development process, and evaluation efforts to-date for the Circle of Life (COL) curricula, HIV/AIDS prevention interventions designed for American Indian and Alaska Native (AI/AN) youth. The curricula are based on Indigenous models of learning and behavior encompassing concepts of Western…

  17. Youth Voter Turnout 1992 to 2004: Estimates from Exit Polls. CIRCLE Fact Sheet.

    ERIC Educational Resources Information Center

    Center for Information and Research on Civic Learning and Engagement, 2005

    2005-01-01

    CIRCLE has issued two releases estimating youth turnout in the 2004 presidential election. The first release was issued on November 3rd and provided the earliest turnout estimates based on National Election Pool (NEP) state and national exit polls and a preliminary vote count. The second was a Fact Sheet released on November 8th which provided…

  18. An Examination of Children's Oral Storytelling in a First Grade Storytelling Circle

    ERIC Educational Resources Information Center

    West, Jean Ann

    2012-01-01

    The purposes of this naturalistic, descriptive study were to examine the stories that children in one first grade classroom told in a storytelling circle, how the children's knowledge, in-school experiences, and out-of-school experiences were reflected in their stories, and how the children used their knowledge and experiences as tools to…

  19. Learners' Perceptions toward Pronunciation Instruction in Three Circles of World Englishes

    ERIC Educational Resources Information Center

    Kang, Okim

    2015-01-01

    From the perspective of World Englishes (i.e., varieties of English in different regions of the world), mutual intelligibility is a key issue for both listeners and speakers. Nevertheless, learners often have an idealized notion of native-speaker spoken norms and may be in favor of more prestigious inner circle models than others. This study…

  20. 1. View to west along Green Street/The Circle showing partial ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. View to west along Green Street/The Circle showing partial southeast elevation and facade (northeast elevation) of Carpenter & Paint Shop, with Medical Storage Building (HABS No. VA-1287-K) and Central Power House (HABS No. VA-1287-J) beyond - Portsmouth Naval Hospital, Carpenter & Paint Shop, Green Street, Portsmouth, Portsmouth, VA

  1. We Modify Each Other's Lessons: The Role of Literacy Work Circles in Developing Professional Community

    ERIC Educational Resources Information Center

    Wardrip, Peter Samuelson; Gomez, Louis M.; Gomez, Kimberley

    2015-01-01

    To address teacher isolation in schools, more reform leaders are finding hope in establishing professional communities as a way to promote continuous school improvement. This case study presents one approach for developing teacher professional community: a teacher work circle. Using the characteristics of professional community created by Kruse,…

  2. Quality Control Circles: A Vehicle for Just-in-Time Implementation.

    ERIC Educational Resources Information Center

    Sepehri, Mehran

    1985-01-01

    Explains just-in-time (JIT) material flow and production, a method of production designed to eliminate waste. Discusses why quality control circles work so well with a JIT system, and describes how several companies have made JIT work for them. (CT)

  3. A plasmonic aptasensor for ultrasensitive detection of thrombin via arrested rolling circle amplification.

    PubMed

    Wang, Sai; Bi, Sai; Wang, Zonghua; Xia, Jianfei; Zhang, Feifei; Yang, Min; Gui, Rijun; Li, Yanhui; Xia, Yanzhi

    2015-05-01

    A sensitive signal generation mechanism for gold nanoparticle growth by reducing gold ions with hydrogen peroxide is applied in a plasmonic aptasensor, achieving naked-eye detection of thrombin at the single-molecule level based on the specific interaction of aptamer-thrombin via an arrested rolling circle amplification to yield horseradish peroxidase (HRP)-mimicking DNAzymes as biocatalysts. PMID:25864665

  4. Mathematical Practices in a Technological Setting: A Design Research Experiment for Teaching Circle Properties

    ERIC Educational Resources Information Center

    Akyuz, Didem

    2016-01-01

    This article documents the classroom mathematical practices observed in a collegiate level teacher education course related to the circle topic. The course, which was prepared as design research, utilized a dynamic geometry environment which influenced the type and nature of the evolved mathematical practices. The study uses emergent perspective…

  5. Circle Talks as Situated Experiential Learning: Context, Identity, and Knowledgeability in "Learning from Reflection"

    ERIC Educational Resources Information Center

    Seaman, Jayson; Rheingold, Alison

    2013-01-01

    This article presents research that used ethnographic and sociolinguistic methods to study ways participants learn through reflection when carried out as a "circle talk." The data indicate that participants in the event (a) invoked different contextual frames that (b) implicated them in various identity positions, which (c) affected how…

  6. New head equivalent phantom for task and image performance evaluation representative for neurovascular procedures occurring in the Circle of Willis

    NASA Astrophysics Data System (ADS)

    Ionita, Ciprian N.; Loughran, Brendan; Jain, Amit; Swetadri Vasan, S. N.; Bednarek, Daniel R.; Levy, Elad; Siddiqui, Adnan H.; Snyder, Kenneth V.; Hopkins, L. N.; Rudin, Stephen

    2012-03-01

    Phantom equivalents of different human anatomical parts are routinely used for imaging system evaluation or dose calculations. The various recommendations on the generic phantom structure given by organizations such as the AAPM, are not always accurate when evaluating a very specific task. When we compared the AAPM head phantom containing 3 mm of aluminum to actual neuro-endovascular image guided interventions (neuro-EIGI) occurring in the Circle of Willis, we found that the system automatic exposure rate control (AERC) significantly underestimated the x-ray parameter selection. To build a more accurate phantom for neuro-EIGI, we reevaluated the amount of aluminum which must be included in the phantom. Human skulls were imaged at different angles, using various angiographic exposures, at kV's relevant to neuro-angiography. An aluminum step wedge was also imaged under identical conditions, and a correlation between the gray values of the imaged skulls and those of the aluminum step thicknesses was established. The average equivalent aluminum thickness for the skull samples for frontal projections in the Circle of Willis region was found to be about 13 mm. The results showed no significant changes in the average equivalent aluminum thickness with kV or mAs variation. When a uniform phantom using 13 mm aluminum and 15 cm acrylic was compared with an anthropomorphic head phantom the x-ray parameters selected by the AERC system were practically identical. These new findings indicate that for this specific task, the amount of aluminum included in the head equivalent must be increased substantially from 3 mm to a value of 13 mm.

  7. Limits of the circles-in-the-sky searches in the determination of cosmic topology of nearly flat universes

    NASA Astrophysics Data System (ADS)

    Gomero, G. I.; Mota, B.; Rebouças, M. J.

    2016-08-01

    An important observable signature of a detectable nontrivial spatial topology of the Universe is the presence in the cosmic microwave background sky of pairs of matching circles with the same distributions of temperature fluctuations—the so-called circles in the sky. Most of the recent attempts to find these circles, including the ones undertaken by the Planck Collaboration, were restricted to antipodal or nearly antipodal circles with radii λ ≥1 5 ° . In the most general search, pairs of circles with deviation from antipodality angles 0 ° ≤θ ≤16 9 ° and radii 1 0 ° ≤λ ≤9 0 ° were investigated. No statistically significant pairs of matching circles were found in the searches so far undertaken. Assuming that the negative result of general search can be confirmed through analysis made with data from Planck and future cosmic microwave background experiments, we examine the question as to whether there are nearly flat universes with compact topology, satisfying Planck constraints on cosmological parameters, that would give rise to circles in the sky whose observable parameters λ and θ fall outside the parameter ranges covered by this general search. We derive the expressions for the deviation from antipodality and for the radius of the circles associated to a pair of elements (γ , γ-1 ) of the holonomy group Γ which define the spatial section of any positively curved universe with a nontrivial compact topology. We show that there is a critical position that maximizes the deviation from antipodality and prove that, no matter how nearly flat the Universe is, it can always have a nontrivial spatial topology that gives rise to circles whose deviation from antipodality θ is larger than 169° and whose radii of the circles λ are smaller than 10° for some observers's positions. This makes it apparent that slightly positively curved nearly flat universes with cosmological parameters within Planck bounds can be endowed with a nontrivial spatial

  8. An inversion formula for the spherical transform in S2 for a special family of circles of integration

    NASA Astrophysics Data System (ADS)

    Salman, Yehonatan

    2016-03-01

    In this article, an inversion formula is obtained for the spherical transform which integrates functions, defined on the unit sphere S2, on circles. The inversion formula is for the case where the circles of integration are obtained by intersections of S2 with hyperplanes passing through a common point overline{a} strictly inside S2. In particular, this yields inversion formulas for two well-known special cases. The first inversion formula is for the special case where the family of circles of integration consists of great circles; this formula is obtained by taking overline{a} = 0. The second inversion formula is for the special case where the circles of integration pass through a common point p on S2; this formula is obtained by taking the limit overline{a}→ p.

  9. A new measuring method for motion accuracy of 3-axis NC equipments based on composite trajectory of circle and non-circle

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Du, Zhengchun; Yang, Jiangguo; Hong, Maisheng

    2011-12-01

    Geometric motion error measurement has been considered as an important task for accuracy enhancement and quality assurance of NC machine tools and CMMs. In consideration of the disadvantages of traditional measuring methods,a new measuring method for motion accuracy of 3-axis NC equipments based on composite trajectory including circle and non-circle(straight line and/or polygonal line) is proposed. The principles and techniques of the new measuring method are discussed in detail. 8 feasible measuring strategies based on different measuring groupings are summarized and optimized. The experiment of the most preferable strategy is carried out on the 3-axis CNC vertical machining center Cincinnati 750 Arrow by using cross grid encoder. The whole measuring time of 21 error components of the new method is cut down to 1-2 h because of easy installation, adjustment, operation and the characteristics of non-contact measurement. Result shows that the new method is suitable for `on machine" measurement and has good prospects of wide application.

  10. UvrD-dependent replication of rolling-circle plasmids in Escherichia coli.

    PubMed

    Bruand, C; Ehrlich, S D

    2000-01-01

    The Escherichia coli UvrD helicase (or helicase II) is known for its involvement in DNA repair. We report that UvrD is required for DNA replication of several different rolling-circle plasmids in E. coli, whereas its homologue, the Rep helicase, is not. Lack of UvrD helicase does not impair the first step of plasmid replication, nicking of the double-stranded origin by the plasmid initiator protein. However, replication proceeds no further without UvrD. Indeed, the nicked plasmid molecules accumulate to a high level in uvrD mutants. We conclude that UvrD is the replicative helicase of various rolling-circle plasmids. This is the first description of a direct implication of UvrD in DNA replication in vivo. PMID:10632890

  11. Violation of Lee-Yang circle theorem for Ising phase transitions on complex networks

    NASA Astrophysics Data System (ADS)

    Krasnytska, M.; Berche, B.; Holovatch, Yu.; Kenna, R.

    2015-09-01

    The Ising model on annealed complex networks with degree distribution decaying algebraically as p(K)∼ K-λ has a second-order phase transition at finite temperature if λ>3 . In the absence of space dimensionality, λ controls the transition strength; classical mean-field exponents apply for λ >5 but critical exponents are λ-dependent if λ < 5 . Here we show that, as for regular lattices, the celebrated Lee-Yang circle theorem is obeyed for the former case. However, unlike on regular lattices where it is independent of dimensionality, the circle theorem fails on complex networks when λ < 5 . We discuss the importance of this result for both theory and experiments on phase transitions and critical phenomena. We also investigate the finite-size scaling of Lee-Yang zeros in both regimes as well as the multiplicative logarithmic corrections which occur at λ=5 .

  12. Bells Galore: Oscillations and circle-map dynamics from space-filling fractal functions

    SciTech Connect

    Puente, C.E.; Cortis, A.; Sivakumar, B.

    2008-10-15

    The construction of a host of interesting patterns over one and two dimensions, as transformations of multifractal measures via fractal interpolating functions related to simple affine mappings, is reviewed. It is illustrated that, while space-filling fractal functions most commonly yield limiting Gaussian distribution measures (bells), there are also situations (depending on the affine mappings parameters) in which there is no limit. Specifically, the one-dimensional case may result in oscillations between two bells, whereas the two-dimensional case may give rise to unexpected circle map dynamics of an arbitrary number of two-dimensional circular bells. It is also shown that, despite the multitude of bells over two dimensions, whose means dance making regular polygons or stars inscribed on a circle, the iteration of affine maps yields exotic kaleidoscopes that decompose such an oscillatory pattern in a way that is similar to the many cases that converge to a single bell.

  13. NanoCluster Beacons as Reporter Probes in Rolling Circle Enhanced Enzyme Activity Detection†

    PubMed Central

    Juul, Sissel; Obliosca, Judy M.; Liu, Cong; Liu, Yen-Liang; Chen, Yu-An; Imphean, Darren M.; Knudsen, Birgitta R.; Ho, Yi-Ping; Leong, Kam W.; Yeh, Hsin-Chih

    2015-01-01

    As a newly developed assay for the detection of endogenous enzyme activity at the single-catalytic-event level, Rolling Circle Enhanced Enzyme Activity Detection (REEAD) has been used to measure enzyme activity in both single human cells and malaria-causing parasites, Plasmodium sp.. Current REEAD assays rely on organic dye-tagged linear DNA probes to report the rolling circle amplification products (RCPs), the cost of which may hinder the widespread use of REEAD. Here we show that a new class of activatable probes, NanoCluster Beacons (NCBs), can simplify the REEAD assays. Easily prepared without any need for purification and capable of large fluorescence enhancement upon hybridization, NCBs are cost-effective and sensitive. Compared to conventional fluorescent probes, NCBs are also more photostable. As demonstrated in reporting the human topoisomerases I (hTopI) cleavage-ligation reaction, the proposed NCBs suggest a read-out format attractive for future REEAD-based diagnostics. PMID:25901841

  14. Semi-automated identification of cones in the human retina using circle Hough transform

    PubMed Central

    Bukowska, Danuta M.; Chew, Avenell L.; Huynh, Emily; Kashani, Irwin; Wan, Sue Ling; Wan, Pak Ming; Chen, Fred K

    2015-01-01

    A large number of human retinal diseases are characterized by a progressive loss of cones, the photoreceptors critical for visual acuity and color perception. Adaptive Optics (AO) imaging presents a potential method to study these cells in vivo. However, AO imaging in ophthalmology is a relatively new phenomenon and quantitative analysis of these images remains difficult and tedious using manual methods. This paper illustrates a novel semi-automated quantitative technique enabling registration of AO images to macular landmarks, cone counting and its radius quantification at specified distances from the foveal center. The new cone counting approach employs the circle Hough transform (cHT) and is compared to automated counting methods, as well as arbitrated manual cone identification. We explore the impact of varying the circle detection parameter on the validity of cHT cone counting and discuss the potential role of using this algorithm in detecting both cones and rods separately. PMID:26713186

  15. [Attachment and attachment-based intervention: the Circle of Security intervention project in Hamburg].

    PubMed

    Ramsauer, Brigitte; Gehrke, Julia; Lotzin, Annett; Powell, Bert; Romer, Georg

    2011-01-01

    Since the early sixties empirical research into early childhood and the parent-infant relationship has increased, commonly informed by attachment theory. The mutually regulated interaction within the attachment and care giving relationship of mother and infant gives this relationship its exceptional emotional quality. Early attachment experiences organize socio-emotional and cognitive development beyond childhood. Attachment theory and research define observable behaviors and the level of internal representations as an intervening variable of the transmission of attachment patterns between mother and child. Basic attachment derived concepts are the starting points of the Circle of Security approach. The Circle of Security Intervention Project in Hamburg for mothers with postpartum mental illness and their infants is described in more detail. Specific aspects are discussed with reference to a diagnostic case study. PMID:21877568

  16. Semi-automated identification of cones in the human retina using circle Hough transform.

    PubMed

    Bukowska, Danuta M; Chew, Avenell L; Huynh, Emily; Kashani, Irwin; Wan, Sue Ling; Wan, Pak Ming; Chen, Fred K

    2015-12-01

    A large number of human retinal diseases are characterized by a progressive loss of cones, the photoreceptors critical for visual acuity and color perception. Adaptive Optics (AO) imaging presents a potential method to study these cells in vivo. However, AO imaging in ophthalmology is a relatively new phenomenon and quantitative analysis of these images remains difficult and tedious using manual methods. This paper illustrates a novel semi-automated quantitative technique enabling registration of AO images to macular landmarks, cone counting and its radius quantification at specified distances from the foveal center. The new cone counting approach employs the circle Hough transform (cHT) and is compared to automated counting methods, as well as arbitrated manual cone identification. We explore the impact of varying the circle detection parameter on the validity of cHT cone counting and discuss the potential role of using this algorithm in detecting both cones and rods separately. PMID:26713186

  17. High-sensitivity temperature sensor based on a droplet-like fiber circle.

    PubMed

    Xie, Jianglei; Xu, Ben; Li, Yi; Kang, Juan; Shen, Changyu; Wang, Jianfeng; Jin, Yongxing; Liu, Honglin; Ni, Kai; Dong, Xinyong; Zhao, Chunliu; Jin, Shangzhong

    2014-06-20

    A low-cost yet high-sensitivity temperature fiber sensor is proposed and demonstrated in this paper. A single-mode fiber with coating is simply bent in a droplet-like circle with a radius of several millimeters. The strong bending induces mode interferences between the silica core mode and the excited modes propagating in the polymer coating. Many resonant dips were observed in the transmission spectra and are found to shift to a shorter wavelength with the increase of environmental temperature. Our linear fitting result of the experimental data shows that the proposed sensor presents high temperature sensitivity up to -3.102  nm/°C, which is even comparable with sensors based on selective liquid-filled photonic crystal fibers. Such high temperature sensitivity results from the large thermo-optical coefficient difference between the silica core and the polymer coating. The influence of a circle radius to the sensitivities is also discussed. PMID:24979444

  18. Collective Motion of Humans in Mosh and Circle Pits at Heavy Metal Concerts

    NASA Astrophysics Data System (ADS)

    Silverberg, Jesse L.; Bierbaum, Matthew; Sethna, James P.; Cohen, Itai

    2013-05-01

    Human collective behavior can vary from calm to panicked depending on social context. Using videos publicly available online, we study the highly energized collective motion of attendees at heavy metal concerts. We find these extreme social gatherings generate similarly extreme behaviors: a disordered gaslike state called a mosh pit and an ordered vortexlike state called a circle pit. Both phenomena are reproduced in flocking simulations demonstrating that human collective behavior is consistent with the predictions of simplified models.

  19. The Astrophysical Signatures of Black Holes: The Horizon, The ISCO, The Ergosphere and The Light Circle

    NASA Astrophysics Data System (ADS)

    Abramowicz, Marek A.

    Three advanced instruments planned for a near future ( LOFT, GRAVITY, THE EVENT HORIZON TELESCOPE) provide unprecedented angular and time resolutions, which allow to probe regions in the immediate vicinity of black holes. We may soon be able to search for the signatures of the super-strong gravity that is characteristic to black holes: the event horizon, the ergosphere, the innermost stable circular orbit (ISCO), and the photon circle. This review discusses a few fundamental problems concerning these theoretical concepts.

  20. PHACE(S) Syndrome With Absent Intracranial Internal Carotid Artery and Anomalous Circle of Willis.

    PubMed

    Winter, Pieta R; Itinteang, Tinte; Leadbitter, Philip; FitzJohn, Trevor; Tan, Swee T

    2015-06-01

    The authors present a case of PHACE(S) (posterior fossa malformations, hemangioma, arterial anomalies, cardiac defects, eye anomalies, and sternal cleft or supraumbilical raphe) syndrome with a right-sided segmental infantile hemangioma, and describe in detail, the associated absent ipsilateral intracranial internal carotid artery and anomalous Circle of Willis. Propranolol therapy led to accelerated, complete involution. Nadolol may reduce the theoretical risk of treating PHACE(S) patients with β-blockers. PMID:26080245

  1. Contralateral stroke during carotid endarterectomy due to abnormalities in the circle of Willis.

    PubMed

    Moritz, Andrea; Koci, Gerda; Steinlechner, Barbara; Hölzenbein, Thomas; Nasel, Christian; Grubhofer, Georg; Dworschak, Martin

    2007-01-01

    Approximately 10-20% of patients will not tolerate cross-clamping of the common carotid artery for carotid endarterectomy procedures. The most frequent causes of neurological deficits are either embolization of particulate matter or cerebral hypoperfusion. Insufficient blood flow through primary collaterals of the circle of Willis is the main reason for hypoperfusion that requires immediate shunt placement. Although excessive preoperative imaging is not indicated in many patients undergoing disobliteration of a stenosed internal carotid artery, there are some patients with particular anatomic constellations who would benefit from a more detailed preoperative work-up. In these cases, the specific risk should be evaluated prior to surgery in order to make plans for appropriate intraoperative management regarding neurologic monitoring and shunt insertion. As regional anesthesia permits early detection of ischemic symptoms, it is advantageous in these patients. We report a case where regional anesthesia allowed early detection of rapidly progressing signs of bi-hemispheric brain ischemia in a patient with diabetes and with at that time unknown severe abnormalities of the circle of Willis. Lack of adequate collateralization was detected only after surgery, in a combined perfusion-magnetic resonance imaging study. In symptomatic diabetics with low-grade stenosis of the internal carotid artery, preoperative assessment of the function of the circle of Willis may therefore be helpful in predicting any increased risk for intraoperative cerebral ischemia. PMID:18043888

  2. White Blood Cell Segmentation by Circle Detection Using Electromagnetism-Like Optimization

    PubMed Central

    Oliva, Diego; Díaz, Margarita; Zaldivar, Daniel; Pérez-Cisneros, Marco; Pajares, Gonzalo

    2013-01-01

    Medical imaging is a relevant field of application of image processing algorithms. In particular, the analysis of white blood cell (WBC) images has engaged researchers from fields of medicine and computer vision alike. Since WBCs can be approximated by a quasicircular form, a circular detector algorithm may be successfully applied. This paper presents an algorithm for the automatic detection of white blood cells embedded into complicated and cluttered smear images that considers the complete process as a circle detection problem. The approach is based on a nature-inspired technique called the electromagnetism-like optimization (EMO) algorithm which is a heuristic method that follows electromagnetism principles for solving complex optimization problems. The proposed approach uses an objective function which measures the resemblance of a candidate circle to an actual WBC. Guided by the values of such objective function, the set of encoded candidate circles are evolved by using EMO, so that they can fit into the actual blood cells contained in the edge map of the image. Experimental results from blood cell images with a varying range of complexity are included to validate the efficiency of the proposed technique regarding detection, robustness, and stability. PMID:23476713

  3. White blood cell segmentation by circle detection using electromagnetism-like optimization.

    PubMed

    Cuevas, Erik; Oliva, Diego; Díaz, Margarita; Zaldivar, Daniel; Pérez-Cisneros, Marco; Pajares, Gonzalo

    2013-01-01

    Medical imaging is a relevant field of application of image processing algorithms. In particular, the analysis of white blood cell (WBC) images has engaged researchers from fields of medicine and computer vision alike. Since WBCs can be approximated by a quasicircular form, a circular detector algorithm may be successfully applied. This paper presents an algorithm for the automatic detection of white blood cells embedded into complicated and cluttered smear images that considers the complete process as a circle detection problem. The approach is based on a nature-inspired technique called the electromagnetism-like optimization (EMO) algorithm which is a heuristic method that follows electromagnetism principles for solving complex optimization problems. The proposed approach uses an objective function which measures the resemblance of a candidate circle to an actual WBC. Guided by the values of such objective function, the set of encoded candidate circles are evolved by using EMO, so that they can fit into the actual blood cells contained in the edge map of the image. Experimental results from blood cell images with a varying range of complexity are included to validate the efficiency of the proposed technique regarding detection, robustness, and stability. PMID:23476713

  4. Concentric circles based simple optical landing aid for vertical takeoff and landing aircrafts

    NASA Astrophysics Data System (ADS)

    Murshid, Syed H.; Enaya, Rayan; Lovell, Gregory L.

    2014-09-01

    Vertical takeoff and landing (VTOL) aircrafts such as helicopters and drones, add a flexible degree of operation to airborne vehicles. In order to operate these devices in low light situations, where it is difficult to determine slope of the landing surface, a lightweight and standalone device is proposed here. This small optical device can be easily integrated into current VTOL systems. An optical projector consisting of low power, light weight, solid state laser along with minimal optics is utilized to illuminate the landing surface with donut shaped circles and coaxial centralized dot. This device can placed anywhere on the aircraft and a properly placed fiber system can be used to illuminate the surface beneath the bottom of the VTOL aircraft in a fashion that during operation, when the aircraft is parallel to the landing surface, the radius between the central dot and outer ring(s) are equidistant for the entire circumference; however, when there the landing surface of the VTOL aircraft is not parallel to the landing strip, the radial distance between two opposite sides of the circle and central dot will be unequal. The larger this distortion, the greater the difference will be between the opposite sides of the circle. Visual confirmation or other optical devices can be used to determine relative alignment of the projector output allowing the pilot to make proper adjustments as they approach the landing surface to ensure safe landings. Simulated and experimental results from a prototype optical projector are presented here.

  5. Adaptive circle-ellipse fitting method for estimating tree diameter based on single terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Bu, Guochao; Wang, Pei

    2016-04-01

    Terrestrial laser scanning (TLS) has been used to extract accurate forest biophysical parameters for inventory purposes. The diameter at breast height (DBH) is a key parameter for individual trees because it has the potential for modeling the height, volume, biomass, and carbon sequestration potential of the tree based on empirical allometric scaling equations. In order to extract the DBH from the single-scan data of TLS automatically and accurately within a certain range, we proposed an adaptive circle-ellipse fitting method based on the point cloud transect. This proposed method can correct the error caused by the simple circle fitting method when a tree is slanted. A slanted tree was detected by the circle-ellipse fitting analysis, then the corresponding slant angle was found based on the ellipse fitting result. With this information, the DBH of the trees could be recalculated based on reslicing the point cloud data at breast height. Artificial stem data simulated by a cylindrical model of leaning trees and the scanning data acquired with the RIEGL VZ-400 were used to test the proposed adaptive fitting method. The results shown that the proposed method can detect the trees and accurately estimate the DBH for leaning trees.

  6. Effects of Local Configuration on the Flow in the Circle of Willis

    NASA Astrophysics Data System (ADS)

    Page, J. H.; Wu, G. X.; Smith, F. T.

    The circle of Willis is a confluence of large arteries which form a ring-like, three-to-six junction. The right and left internal carotid arteries and the basilar artery carry blood up the neck and meet a circular arrangement of three communicating arteries at the base of the cerebrum. Six cerebral arteries then depart from the circle of Willis towards different areas of the brain. The circle of Willis plays a pivotal role in allowing the correct blood distribution in the cerebrum. The presence of the communicating arteries provides routes along which blood may flow in order to moderate or effect changes in the efferent flux distribution, in response to variations in the supply of and local demands for blood[1]. The anterior communicating artery is a common site for the occurrence of cerebral aneurysms, an abnormal bulge in the arterial wall which grows over time [2]. Such cerebral aneurysms can eventually rupture leading to a subarachnoid haemorrhage [2]. It is widely thought that forces exerted by the blood on the arterial wall, such as wall pressure and wall shear stress, make a significant contribution to the growth of aneurysms [3].

  7. Circles on pommel horse with a suspended aid: mass-centre rotation and hip joint moment.

    PubMed

    Fujihara, Toshiyuki; Gervais, Pierre

    2012-01-01

    This is the second study of the series, and its aim was to investigate the influence of using the suspended aid on circle kinetics. In addition to the kinematic data recorded for part one (Fujihara & Gervais, 2012), the pommel reaction forces and the force applied from the suspended aid (aid reaction force) were analysed in relation to the motion of a whole-body mass centre. The hip joint moment was also computed by combining all segments in the lower extremities into a single rigid segment. Generally, the use of the aid changed the magnitude of the mass-centre trajectory or horizontal pommel reaction forces but not their patterns. The results also showed that the net hip joint moment was altered during circles with the aid. In summary, a suspended aid can be used as a progression for a variety of goals because it allows gymnasts to practise circles which would not be possible without the aid. When a suspended aid is used, however, practitioners should be aware of the possible kinetic alteration caused by the external force from the aid. PMID:22697492

  8. A U.K. cost-benefit analysis of circles of support and accountability interventions.

    PubMed

    Elliott, Ian A; Beech, Anthony R

    2013-06-01

    Circles of Support and Accountability (CoSA) aim to augment sex offender risk management at the point of community reentry by facilitating "Circles" of volunteers who provide support, guidance, and advice, while ensuring that the offender remains accountable for their actions. In this study, the authors provide (a) a rapid evidence assessment of the effectiveness of CoSA in reducing reoffending, and (b) a U.K. cost-benefit analysis for CoSA when compared to the criminal justice costs of reoffending. From the study analysis, the average cost of a "Circle" was estimated to be £11,303 per annum and appears to produce a 50% reduction in reoffending (sexual and nonsexual), as the estimated cost of reoffending was estimated to be £147,161 per offender, per annum. Based on a hypothetical cohort of 100 offenders--50 of whom receive CoSA and 50 of whom do not--investment in CoSA appears to provide a cost saving of £23,494 and a benefit-cost ratio of 1.04. Accounting for estimates that the full extent of the cost to society may be 5 to 10 times the tangible costs substantially increases estimated cost savings related to CoSA. PMID:22565198

  9. Hydraulic characteristics of an underdrained irrigation circle, Muskegon County, wastewater disposal system, Michigan

    USGS Publications Warehouse

    McDonald, M.G.

    1981-01-01

    Muskegon County, Michigan, disposes of waste water by spray irrigating farmland on its waste-disposal site. Buried drains in the highly permeable unconfined aquifer at the site control the level of the water table. Hydraulic conductivity of the aquifer and drain-leakance, the reciprocal of resistance to flow into the drains, was determined at a representative irrigation circle while calibrating a model of the ground-water flow system. Hydraulic conductivity is 0.00055 meter per second in the north zone of the circle and 0.00039 meter per second in the south zone. Drain leakance is low in both zones: 2.9 x 10-6 meters per second in the north and 9.5 x 10-6 meters per second in the south. Low drain leakance is responsible for waterlogging when irrigation rates are maintained at design levels. The capacity of the study circle to accept waste water is 35 percent less than design capacity.

  10. CircleRides: developing an older adult transportation application and evaluating feedback.

    PubMed

    Heinz, Melinda; Kelly, Norene

    2015-05-01

    The purpose of the current study was to assess perceptions of CircleRides, a paper prototype of a service website designed to meet older adult transportation needs. Researchers used purposive sampling to conduct two focus groups comprised of older adults to obtain feedback on the CircleRides prototype at the beginning of its iterative design process. One focus group was conducted in a continuing care retirement community (n = 13) and the other in an independent living community for older adults (n = 11). The study assessed perceptions of the CircleRides prototype as well as self-reported older adult transportation preferences and needs. Three themes emerged from the data: (a) trust and concern, (b) socialization, and (c) flexibility and options. Researchers found that participants are interested in transportation options; however, concern exists about trusting a new system or prototype that has not established a reputation. Findings from the current study offer lessons learned for future iterations and for creating transportation prototypes for older adults. PMID:25643351

  11. Numerical Simulation of the blood flow behavior in the circle of  Willis

    PubMed Central

    Razavi, Seyyed Esmail; Sahebjam, Rana

    2014-01-01

    Introduction: This paper represents the numerical simulation of blood flow in the circle of Willis (CoW). Circle of Willis is responsible for the oxygenated blood distribution into the cerebral mass. To investigate the blood behavior, two Newtonian and non-Newtonian viscosity models were considered and the results were compared under steady state conditions. Methods: Methodologically, the arterial geometry was obtained using 3D magnetic resonance angiography (MRA) data. The blood flow through the cerebral vasculature was considered to be steady and laminar, and the Galerkin’s finite element method was applied to solve the systems of non-linear Navier-Stokes equations. Results: Flow patterns including flow rates and shear rates were obtained through the simulation. The minimal magnitude of shear rates was much greater than 100 s-1 through the larger arteries; thus, the non-Newtonian blood viscosity tended to approach the constant limit of infinite shear viscosity through the CoW. So, in larger arteries the non-Newtonian nature of blood was less dominant and it would be treated as a Newtonian fluid. The only exception was the anterior communicating artery (ACoA) in which the blood flow showed different behavior for the Newtonian and non-Newtonian cases. Conclusion By comparing the results it was concluded that the Newtonian viscosity assumption of blood flow through the healthy, complete circle of Willis under the normal and steady conditions would be acceptably accurate. PMID:25035852

  12. Spindle error motion measurement using concentric circle grating and phase modulation interferometers

    NASA Astrophysics Data System (ADS)

    Aketagawa, M.; Madden, M.; Uesugi, S.; Kumagai, T.; Maeda, Y.; Okuyama, E.

    2012-11-01

    In the conventional methods to measure radial, axial and angular motions of spindles, complicated artifacts with relative large volume (such as two balls linked with a cylinder) are required. Small volume artifact is favorable from the viewpoint of the accurate and practical measurement of the spindle motion. This paper describes a concurrent measurement of spindle radial, axial and angular motions using concentric circle grating and phase modulation interferometers. In the measurement, the concentric circle grating with fine pitch is installed on top of the spindle of interest. The grating is a reference artifact in the method. Three optical sensors are fixed over the concentric circle grating, and observe the proper positions of the grating. The optical sensor consists of a frequency modulated laser diode as a light source, and two interferometers. One interferometer observes an interference fringe between reflected light form a fixed mirror and 0-th order diffraction light from the grating to measure the axial motion. Another interferometer observes an interference fringe between +/-2nd diffraction lights from the grating to measure the radial motion. Using three optical sensors, three radial displacements and three axial displacements of the proper observed position of the grating can be measured. From these measured displacements, radial, axial and angular motions of the spindle can be calculated concurrently. In the paper, a measurement instrument, a novel fringe interpolation technique by sinusoidal phase modulation and experimental results are discussed.

  13. Amplified and multiplexed detection of DNA using the dendritic rolling circle amplified synthesis of DNAzyme reporter units.

    PubMed

    Wang, Fuan; Lu, Chun-Hua; Liu, Xiaoqing; Freage, Lina; Willner, Itamar

    2014-02-01

    The amplified, highly sensitive detection of DNA using the dendritic rolling circle amplification (RCA) is introduced. The analytical platform includes a circular DNA and a structurally tailored hairpin structure. The circular nucleic acid template includes a recognition sequence for the analyte DNA (the Tay-Sachs mutant gene), a complementary sequence to the Mg(2+)-dependent DNAzyme, and a sequence identical to the loop region of the coadded hairpin structure. The functional hairpin in the system consists of the analyte-sequence that is caged in the stem region and a single-stranded loop domain that communicates with the RCA product. The analyte activates the RCA process, leading to DNA chains consisting of the Mg(2+)-dependent DNAzyme and sequences that are complementary to the loop of the functional hairpin structure. Opening of the coadded hairpin releases the caged analyte sequence, resulting in the dendritic RCA-induced synthesis of the Mg(2+)-dependent DNAzyme units. The DNAzyme-catalyzed cleavage of a fluorophore/quencher-modified substrate leads to a fluorescence readout signal. The method enabled the analysis of the target DNA with a detection limit corresponding to 1 aM. By the design of two different circular DNAs that include recognition sites for two different target genes, complementary sequences for two different Mg(2+)-dependent DNAzyme sequences and two different functional hairpin structures, the dendritic RCA-stimulated multiplexed analysis of two different genes is demonstrated. The amplified dendritic RCA detection of DNA is further implemented to yield the hemin/G-quadruplex horseradish peroxidase (HRP)-mimicking DNAzyme as catalytic labels that provide colorimetric or chemiluminescent readout signals. PMID:24377284

  14. Improving Self-Esteem of Women Offenders through Process-based Writing in a Learning Circle: An Exploratory Study.

    ERIC Educational Resources Information Center

    Stino, Zandra H.; Palmer, Barbara C.

    1998-01-01

    Over 18 weeks, nine female offenders worked in a collaborative learning circle with process-based writing (prewriting, drafting, sharing, revising, editing, proofreading, publishing). Most showed a significant increase in self-esteem. (SK)

  15. "Really," "Not Possible," "I Can't Believe It": Exploring Informational Text in Literature Circles

    ERIC Educational Resources Information Center

    Barone, Diane; Barone, Rebecca

    2016-01-01

    Fifth graders' interpretations of nonfiction or informational text were explored. Each literature circle group read and responded to informational text. Discoveries included that students' conversations and written responses were closely connected to text and that students created multimodal responses.

  16. COMMENT: Comment on 'On the uncertainty relations and squeezed states for the quantum mechanics on a circle'

    NASA Astrophysics Data System (ADS)

    Trifonov, D. A.

    2003-02-01

    It is shown by examples that the position uncertainty on a circle, proposed recently by Kowalski and Rembielinski (2002 J. Phys. A:Math. Gen. 35 1405) is not consistent with the state localization. We argue that the relevant uncertainties and uncertainty relations (URs) on a circle are those based on the Gram-Robertson matrix. Several of these generalized URs are displayed and related criteria for squeezed states are discussed.

  17. Revisiting the vicious circle of dry eye disease: a focus on the pathophysiology of meibomian gland dysfunction.

    PubMed

    Baudouin, Christophe; Messmer, Elisabeth M; Aragona, Pasquale; Geerling, Gerd; Akova, Yonca A; Benítez-del-Castillo, José; Boboridis, Kostas G; Merayo-Lloves, Jesús; Rolando, Maurizio; Labetoulle, Marc

    2016-03-01

    Meibomian gland dysfunction (MGD) is the most frequent cause of dry eye disease (DED). Eyelid inflammation, microbial growth, associated skin disorders as well as potentially severe corneal complications culminate to make MGD a complex multifactorial disorder. It is probable that MGD is a heterogeneous condition arising from any combination of the following five separate pathophysiological mechanisms: eyelid inflammation, conjunctival inflammation, corneal damage, microbiological changes and DED resulting from tear film instability. The pathogenesis of both MGD and DED can be described in terms of a 'vicious circle': the underlying pathophysiological mechanisms of DED and MGD interact, resulting in a double vicious circle. The MGD vicious circle is self-stimulated by microbiological changes, which results in increased melting temperature of meibum and subsequent meibomian gland blockage, reinforcing the vicious circle of MGD. Meibomian gland blockage, dropout and inflammation directly link the two vicious circles. MGD-associated tear film instability provides an entry point into the vicious circle of DED and leads to hyperosmolarity and inflammation, which are both a cause and consequence of DED. Here we propose a new pathophysiological scheme for MGD in order to better identify the pathological mechanisms involved and to allow more efficient targeting of therapeutics. Through better understanding of this scheme, MGD may gain true disease status rather than being viewed as a mere dysfunction. PMID:26781133

  18. Crustal Strike-Slip Faulting along Small Circle Paths in the Northwestern United States

    NASA Astrophysics Data System (ADS)

    Brocher, T. M.; Wells, R. E.; Lamb, A. P.; Weaver, C. S.

    2015-12-01

    Late Cenozoic and Quaternary faults, seismicity lineaments, and focal mechanisms provide evidence that clockwise rotation of Washington and Oregon is accommodated by north-directed thrusting and strike-slip deformation in the Washington segment of the Cascadia forearc. Curvilinear NW- to NNW-trending high-angle strike-slip faults and seismicity lineaments define small circles around an Euler pole (117.7°W, 47.9°N) of rotation relative to North America that approximates GPS-derived poles for the rotation of eastern Washington and the Snake River Plain. Although the lengths of strike-slip faults that follow small circle paths suggest maximum earthquake magnitudes of M6.6 to M7.2, their slip rates calculated from the Euler pole are low (0.3 to 0.5 mm/yr). Many normal faults in the Lewis and Clark Zone in Montana, the Centennial fault system north of the Snake River Plain, west of the Wasatch Front, in the northern Basin and Range, and locally east of the Oregon Cascade arc are radial to this pole of rotation, suggesting that these normal faults help accommodate this crustal rotation. Regions undergoing contraction in western Washington and northwestern Oregon are separated from those to the east undergoing extension by lines radial to the Euler pole. In our regional kinematic model, dextral faults along small circles connect SW-directed crustal extension in the Intermountain Seismic Belt and E-directed extension in the Cascade arc south of Mount Hood to N-directed contraction in the Olympic Peninsula, Puget Lowland, and the Yakima Fold and Thrust Belt. The lack of Quaternary faulting and seismicity in the Oregon segment of the forearc is consistent with its clockwise rotation as a rigid block. Potential drivers of the crustal rotation include westward slab rollback and the Yellowstone geoid high, and the overall velocity field may integrate the response of rotating blocks and distributed deformation between them.

  19. An Exploration of Social Circles and Prescription Drug Abuse Through Twitter

    PubMed Central

    2013-01-01

    Background Prescription drug abuse has become a major public health problem. Relationships and social context are important contributing factors. Social media provides online channels for people to build relationships that may influence attitudes and behaviors. Objective To determine whether people who show signs of prescription drug abuse connect online with others who reinforce this behavior, and to observe the conversation and engagement of these networks with regard to prescription drug abuse. Methods Twitter statuses mentioning prescription drugs were collected from November 2011 to November 2012. From this set, 25 Twitter users were selected who discussed topics indicative of prescription drug abuse. Social circles of 100 people were discovered around each of these Twitter users; the tweets of the Twitter users in these networks were collected and analyzed according to prescription drug abuse discussion and interaction with other users about the topic. Results From November 2011 to November 2012, 3,389,771 mentions of prescription drug terms were observed. For the 25 social circles (n=100 for each circle), on average 53.96% (SD 24.3) of the Twitter users used prescription drug terms at least once in their posts, and 37.76% (SD 20.8) mentioned another Twitter user by name in a post with a prescription drug term. Strong correlation was found between the kinds of drugs mentioned by the index user and his or her network (mean r=0.73), and between the amount of interaction about prescription drugs and a level of abusiveness shown by the network (r=0.85, P<.001). Conclusions Twitter users who discuss prescription drug abuse online are surrounded by others who also discuss it—potentially reinforcing a negative behavior and social norm. PMID:24014109

  20. Curved grating fabrication techniques for concentric-circle grating, surface-emitting semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Jordan, Rebecca H.; King, Oliver; Wicks, Gary W.; Hall, Dennis G.; Anderson, Erik H.; Rooks, Michael J.

    1993-01-01

    We describe the fabrication and operational characteristics of a novel, surface-emitting semiconductor laser that makes use of a concentric-circle grating to both define its resonant cavity and to provide surface emission. A properly fabricated circular grating causes the laser to operate in radially inward- and outward-going circular waves in the waveguide, thus, introducing the circular symmetry needed for the laser to emit a beam with a circular cross-section. The basic circular-grating-resonator concept can be implemented in any materials system; an AlGaAs/GaAs graded-index, separate confinement heterostructure (GRINSCH), single-quantum-well (SQW) semiconductor laser, grown by molecular beam epitaxy (MBE), was used for the experiments discussed here. Each concentric-circle grating was fabricated on the surface of the AlGaAs/GaAs semiconductor laser. The circular pattern was first defined by electron-beam (e-beam) lithography in a layer of polymethylmethacrylate (PMMA) and subsequently etched into the semiconductor surface using chemically-assisted (chlorine) ion-beam etching (CAIBE). We consider issues that affect the fabrication and quality of the gratings. These issues include grating design requirements, data representation of the grating pattern, and e-beam scan method. We provide examples of how these techniques can be implemented and their impact on the resulting laser performance. A comparison is made of the results obtained using two fundamentally different electron-beam writing systems. Circular gratings with period lambda = 0.25 microns and overall diameters ranging from 80 microns to 500 microns were fabricated. We also report our successful demonstration of an optically pumped, concentric-circle grating, semiconductor laser that emits a beam with a far-field divergence angle that is less than one degree. The emission spectrum is quite narrow (less than 0.1 nm) and is centered at wavelength lambda = 0.8175 microns.

  1. The arterial circle of the brain, its branches and connections in selected representatives of the Antilopinae.

    PubMed

    Frąckowiak, Hieronim; Dębiński, Dariusz; Komosa, Marcin; Zdun, Maciej

    2015-07-01

    The arterial circle of the brain, that is, the circle of Willis, and its branches in ruminants have been chiefly described in farm animals and only in selected wild species. In view of the deficit of information about this vascular region in numerous other species of the Ruminantia, the arteries of the encephalic base were analyzed in five antelope species representing different genera of the Bovidae, Antilopinae. Specimens of the following species were examined: springbuck (Antidorcas marsupialis), blackbuck (Antilope cervicapra), dik-dik (Madoqua kirkii), saiga (Saiga tatarica), and oribi (Ourebia ourebi). Post-autopsy material received from domestic zoological gardens was used to inject the bilateral common carotid arteries with a stained acetone solution of vinyl superchloride. When the material was polymerized, the specimens were macerated enzymatically. The process resulted in casts of arteries of the head and encephalic base on a skeletal scaffold. The investigations revealed that the bilateral components of the arterial circle of the brain, that is, the rostral cerebral artery and caudal communicating artery, arose from the division of the intracranial segment of the internal carotid artery, which emerges from the rostral epidural rete mirabile. The extracranial segment of the internal carotid artery was obliterated. In consequence of this process, the blood reaches the brain chiefly from the maxillary artery. The research proved that the arteries of the encephalic base in the Antilopinae are most similar to the vessels described in antelopes of Tragelaphus, Taurotragus, and Boselaphus genera and small domestic ruminants. However, they are different from the arterial pattern of the encephalic base in bovines and other species classified as the Bovini. PMID:25694115

  2. Imagining circles--Empirical data and a perceptual model for the arc-size illusion.

    PubMed

    Schmidtmann, Gunnar; Ouhnana, Marouane; Loffler, Gunter; Kingdom, Frederick A A

    2016-04-01

    An essential part of visual object recognition is the evaluation of the curvature of both an object's outline as well as the contours on its surface. We studied a striking illusion of visual curvature--the arc-size illusion (ASI)--to gain insight into the visual coding of curvature. In the ASI, short arcs are perceived as flatter (less curved) compared to longer arcs of the same radius. We investigated if and how the ASI depends on (i) the physical size of the stimulus and (ii) on the length of the arc. Our results show that perceived curvature monotonically increases with arc length up to an arc angle of about 60°, thereafter remaining constant and equal to the perceived curvature of a full circle. We investigated if the misjudgment of curvature in the ASI translates into predictable biases for three other perceptual tasks: (i) judging the position of the centre of circular arcs; (ii) judging if two circular arcs fall on the circumference of the same (invisible) circle and (iii) interpolating the position of a point on the circumference of a circle defined by two circular arcs. We found that the biases in all the above tasks were reliably predicted by the same bias mediating the ASI. We present a simple model, based on the central angle subtended by an arc, that captures the data for all tasks. Importantly, we argue that the ASI and related biases are a consequence of the fact that an object's curvature is perceived as constant with viewing distance, in other words is perceptually scale invariant. PMID:26902729

  3. Two-photon microscopy with double-circle trajectories for in vivo cerebral blood flow measurements

    NASA Astrophysics Data System (ADS)

    Landolt, Andrin; Obrist, Dominik; Wyss, Matthias; Barrett, Matthew; Langer, Dominik; Jolivet, Renaud; Soltysinski, Tomasz; Roesgen, Thomas; Weber, Bruno

    2013-05-01

    Scanning microscopes normally use trajectories which produce full-frame images of an object at a low frame rate. Time-resolved measurements are possible if scans along a single line are repeated at a high rate. In conjunction with fluorescence labeling techniques, in vivo recording of blood flow in single capillaries is possible. The present work investigates scanning with double-circle trajectories to measure blood flow simultaneously in several vessels of a capillary network. With the trajectory centered near a bifurcation, a double circle crosses each vessel twice, creating a sensing gate for passing dark red blood cells in fluorescently labeled plasma. From the stack of scans repeated at 1,300 Hz, the time-resolved velocity is retrieved using an image correlation approach. Single bifurcation events can be identified from a few fluorescently labeled red blood cells. The applicability of the method for in vivo measurements is illustrated on the basis of two-photon laser scanning microscopy of the cerebral capillary network of mice. Its performance is assessed with synthetic data generated from a two-phase model for the perfusion in a capillary network. The calculation of velocities is found to be sufficiently robust for a wide range of conditions. The achievable limits depend significantly on the experimental conditions and are estimated to be in the 1 μm/s (velocity) and 0.1 s (time resolution) ranges, respectively. Some manual fine-tuning is required for optimal performance in terms of accuracy and time resolution. Further work may lead to improved reliability with which bifurcation events are identified in the algorithm and to include red blood cell flux and hematocrit measurements. With the capability for time-resolved measurements in all vessels of a bifurcation, double-circle scanning trajectories allow a detailed study of the dynamics in vascular networks.

  4. 3-D RESERVOIR AND STOCHASTIC FRACTURE NETWORK MODELING FOR ENHANCED OIL RECOVERY, CIRCLE RIDGE PHOSPHORIA/TENSLEEP RESERVOIR, WIND RIVER RESERVATION, ARAPAHO AND SHOSHONE TRIBES, WYOMING

    SciTech Connect

    Paul La Pointe; Jan Hermanson; Robert Parney; Thorsten Eiben; Mike Dunleavy; Ken Steele; John Whitney; Darrell Eubanks; Roger Straub

    2002-11-18

    This report describes the results made in fulfillment of contract DE-FG26-00BC15190, ''3-D Reservoir and Stochastic Fracture Network Modeling for Enhanced Oil Recovery, Circle Ridge Phosphoria/Tensleep Reservoir, Wind River Reservation, Arapaho and Shoshone Tribes, Wyoming''. The goal of this project is to improve the recovery of oil from the Tensleep and Phosphoria Formations in Circle Ridge Oilfield, located on the Wind River Reservation in Wyoming, through an innovative integration of matrix characterization, structural reconstruction, and the characterization of the fracturing in the reservoir through the use of discrete fracture network models. Fields in which natural fractures dominate reservoir permeability, such as the Circle Ridge Field, often experience sub-optimal recovery when recovery processes are designed and implemented that do not take advantage of the fracture systems. For example, a conventional waterflood in a main structural block of the Field was implemented and later suspended due to unattractive results. It is estimated that somewhere less than 20% of the OOIP in the Circle Ridge Field have been recovered after more than 50 years' production. Marathon Oil Company identified the Circle Ridge Field as an attractive candidate for several advanced IOR processes that explicitly take advantage of the natural fracture system. These processes require knowledge of the distribution of matrix porosity, permeability and oil saturations; and understanding of where fracturing is likely to be well-developed or poorly developed; how the fracturing may compartmentalize the reservoir; and how smaller, relatively untested subthrust fault blocks may be connected to the main overthrust block. For this reason, the project focused on improving knowledge of the matrix properties, the fault block architecture and to develop a model that could be used to predict fracture intensity, orientation and fluid flow/connectivity properties. Knowledge of matrix properties was

  5. Cone-beam reconstruction for the two-circles-plus-one-line trajectory

    NASA Astrophysics Data System (ADS)

    Lu, Yanbin; Yang, Jiansheng; Emerson, John W.; Mao, Heng; Zhou, Tie; Si, Yuanzheng; Jiang, Ming

    2012-05-01

    The Kodak Image Station In-Vivo FX has an x-ray module with cone-beam configuration for radiographic imaging but lacks the functionality of tomography. To introduce x-ray tomography into the system, we choose the two-circles-plus-one-line trajectory by mounting one translation motor and one rotation motor. We establish a reconstruction algorithm by applying the M-line reconstruction method. Numerical studies and preliminary physical phantom experiment demonstrate the feasibility of the proposed design and reconstruction algorithm.

  6. The Low-Metallicity Galaxy, I Zw 18 (Z=1/50 Z(circle dot))

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.

    2003-01-01

    Both observations and evolutionary models indicate that rotation becomes a more important factor at lower metallicities. Some important effects of rotation include: increasing the rate of mass-loss; lowering the effective gravity; altering the evolutionary track on the Hertzsprung-Russell Diagram (HRD); extending the main-sequence phase (both on the HR diagram and in time); and mixing of CNO-processed elements up to the stellar surface. We discuss these effects for massive stars in the low-metallicity galaxy, I Zw 18 (Z=1/50 Z(circle dot)) and their implications for the first stars.

  7. [From Comte to Carnap. Marcel Boll and the introduction of the Vienna Circle in France].

    PubMed

    Schöttler, Peter

    2015-01-01

    The issue of the introduction of viennese "scientific philosophy" in France appears to be resolved. However, the rediscovery of the positivist physicist Marcel Boll (1886-1971), who was the first-well before Louis Rougier-to draw the French public's attention to the works of Schlick, Frank, and Carnap, obliges us to rethink the passage from traditional positivism to neo-positivism during the 1920s and 1930s. The French reception of the Vienna circle can be dated earlier than accepted and is more profound than usualy assumed. PMID:25914078

  8. A miniature closed-circle flow cell for high photon flux X-ray scattering experiments.

    PubMed

    Sahle, Ch J; Henriquet, C; Schroer, M A; Juurinen, I; Niskanen, J; Krisch, M

    2015-11-01

    A closed-circle miniature flow cell for high X-ray photon flux experiments on radiation-sensitive liquid samples is presented. The compact cell is made from highly inert material and the flow is induced by a rotating magnetic stir bar, which acts as a centrifugal pump inside the cell. The cell is ideal for radiation-sensitive yet precious or hazardous liquid samples, such as concentrated acids or bases. As a demonstration of the cell's capabilities, X-ray Raman scattering spectroscopy data on the oxygen K-edge of liquid water under ambient conditions are presented. PMID:26524322

  9. Circum-Arctic Resource Appraisal: Estimates of Undiscovered Oil and Gas North of the Arctic Circle

    USGS Publications Warehouse

    Bird, Kenneth J.; Charpentier, Ronald R.; Gautier, Donald L.; Houseknecht, David W.; Klett, Timothy R.; Pitman, Janet K.; Moore, Thomas E.; Schenk, Christopher J.; Tennyson, Marilyn E.; Wandrey, Craig R.

    2008-01-01

    The U.S. Geological Survey (USGS) has completed an assessment of undiscovered conventional oil and gas resources in all areas north of the Arctic Circle. Using a geology-based probabilistic methodology, the USGS estimated the occurrence of undiscovered oil and gas in 33 geologic provinces thought to be prospective for petroleum. The sum of the mean estimates for each province indicates that 90 billion barrels of oil, 1,669 trillion cubic feet of natural gas, and 44 billion barrels of natural gas liquids may remain to be found in the Arctic, of which approximately 84 percent is expected to occur in offshore areas.

  10. Aircraft Detection from VHR Images Based on Circle-Frequency Filter and Multilevel Features

    PubMed Central

    Gao, Feng; Li, Bo

    2013-01-01

    Aircraft automatic detection from very high-resolution (VHR) images plays an important role in a wide variety of applications. This paper proposes a novel detector for aircraft detection from very high-resolution (VHR) remote sensing images. To accurately distinguish aircrafts from background, a circle-frequency filter (CF-filter) is used to extract the candidate locations of aircrafts from a large size image. A multi-level feature model is then employed to represent both local appearance and spatial layout of aircrafts by means of Robust Hue Descriptor and Histogram of Oriented Gradients. The experimental results demonstrate the superior performance of the proposed method. PMID:24163637

  11. Quadrature formulas on the unit circle with prescribed nodes and maximal domain of validity

    NASA Astrophysics Data System (ADS)

    Bultheel, Adhemar; Daruis, Leyla; González-Vera, Pablo

    2009-09-01

    In this paper we investigate the Szego-Radau and Szego-Lobatto quadrature formulas on the unit circle. These are (n+m)-point formulas for which m nodes are fixed in advance, with m=1 and m=2 respectively, and which have a maximal domain of validity in the space of Laurent polynomials. This means that the free parameters (free nodes and positive weights) are chosen such that the quadrature formula is exact for all powers zj, -p<=j<=p, with p=p(n,m) as large as possible.

  12. NanoCluster Beacons as reporter probes in rolling circle enhanced enzyme activity detection

    NASA Astrophysics Data System (ADS)

    Juul, Sissel; Obliosca, Judy M.; Liu, Cong; Liu, Yen-Liang; Chen, Yu-An; Imphean, Darren M.; Knudsen, Birgitta R.; Ho, Yi-Ping; Leong, Kam W.; Yeh, Hsin-Chih

    2015-04-01

    As a newly developed assay for the detection of endogenous enzyme activity at the single-catalytic-event level, Rolling Circle Enhanced Enzyme Activity Detection (REEAD) has been used to measure enzyme activity in both single human cells and malaria-causing parasites, Plasmodium sp. Current REEAD assays rely on organic dye-tagged linear DNA probes to report the rolling circle amplification products (RCPs), the cost of which may hinder the widespread use of REEAD. Here we show that a new class of activatable probes, NanoCluster Beacons (NCBs), can simplify the REEAD assays. Easily prepared without any need for purification and capable of large fluorescence enhancement upon hybridization, NCBs are cost-effective and sensitive. Compared to conventional fluorescent probes, NCBs are also more photostable. As demonstrated in reporting the human topoisomerases I (hTopI) cleavage-ligation reaction, the proposed NCBs suggest a read-out format attractive for future REEAD-based diagnostics.As a newly developed assay for the detection of endogenous enzyme activity at the single-catalytic-event level, Rolling Circle Enhanced Enzyme Activity Detection (REEAD) has been used to measure enzyme activity in both single human cells and malaria-causing parasites, Plasmodium sp. Current REEAD assays rely on organic dye-tagged linear DNA probes to report the rolling circle amplification products (RCPs), the cost of which may hinder the widespread use of REEAD. Here we show that a new class of activatable probes, NanoCluster Beacons (NCBs), can simplify the REEAD assays. Easily prepared without any need for purification and capable of large fluorescence enhancement upon hybridization, NCBs are cost-effective and sensitive. Compared to conventional fluorescent probes, NCBs are also more photostable. As demonstrated in reporting the human topoisomerases I (hTopI) cleavage-ligation reaction, the proposed NCBs suggest a read-out format attractive for future REEAD-based diagnostics. Electronic

  13. [Capoeira circle or sports academy? The emergence of modern styles of capoeira and their global context].

    PubMed

    Assunção, Matthias Röhrig

    2014-01-01

    The emergence of the modern styles of capoeira should be considered in the global context of the modernization of martial arts currently in progress in Europe and Asia on the one hand, and the new phase of Afro-descendant modernity on the other. The confrontation between the capoeira, jiu-jitsu and other martial arts circles led mestre Bimba to develop his regional Bahian fighting style. The revival of traditional capoeira as Angolan capoeira led by mestre Pastinha is part of the broader movement of affirmation of Afro-Bahian culture in Salvador and the growing visibility of the Afro-descendant body in the Atlantic world. PMID:24554135

  14. Bathymetric and Hydraulic Survey of the Matanuska River near Circle View Estates, Alaska

    USGS Publications Warehouse

    Conaway, Jeffrey S.

    2008-01-01

    An acoustic Doppler current profiler interfaced with a differentially corrected global positioning system was used to map bathymetry and multi-dimensional velocities on the Matanuska River near Circle View Estates, Alaska. Data were collected along four spur dikes and a bend in the river during a period of active bank erosion. These data were collected as part of a larger investigation into channel processes being conducted to aid land managers with development of a long-term management plan for land near the river. The banks and streambed are composed of readily erodible material and the braided channels frequently scour and migrate. Lateral channel migration has resulted in the periodic loss of properties and structures along the river for decades. For most of the survey, discharge of the Matanuska River was less than the 25th percentile of long-term streamflow. Despite this relatively low flow, measured water velocities were as high as 15 feet per second. The survey required a unique deployment of the acoustic Doppler current profiler in a tethered boat that was towed by a small inflatable raft. Data were collected along cross sections and longitudinal profiles. The bathymetric and velocity data document river conditions before the installation of an additional spur dike in 2006 and during a period of bank erosion. Data were collected along 1,700 feet of river in front of the spur dikes and along 1,500 feet of an eroding bank. Data collected at the nose of spur dikes 2, 3, and 4 were selected to quantify the flow hydraulics at the locations subject to the highest velocities. The measured velocities and flow depths were greatest at the nose of the downstream-most spur dike. The maximum point velocity at the spur dike nose was 13.3 feet per second and the maximum depth-averaged velocity was 11.6 feet per second. The maximum measured depth was 12.0 feet at the nose of spur dike 4 and velocities greater than 10 feet per second were measured to a depth of 10 feet

  15. Revisiting the vicious circle of dry eye disease: a focus on the pathophysiology of meibomian gland dysfunction

    PubMed Central

    Baudouin, Christophe; Messmer, Elisabeth M; Geerling, Gerd; Akova, Yonca A; Benítez-del-Castillo, José; Boboridis, Kostas G; Merayo-Lloves, Jesús; Rolando, Maurizio; Labetoulle, Marc

    2016-01-01

    Meibomian gland dysfunction (MGD) is the most frequent cause of dry eye disease (DED). Eyelid inflammation, microbial growth, associated skin disorders as well as potentially severe corneal complications culminate to make MGD a complex multifactorial disorder. It is probable that MGD is a heterogeneous condition arising from any combination of the following five separate pathophysiological mechanisms: eyelid inflammation, conjunctival inflammation, corneal damage, microbiological changes and DED resulting from tear film instability. The pathogenesis of both MGD and DED can be described in terms of a ‘vicious circle’: the underlying pathophysiological mechanisms of DED and MGD interact, resulting in a double vicious circle. The MGD vicious circle is self-stimulated by microbiological changes, which results in increased melting temperature of meibum and subsequent meibomian gland blockage, reinforcing the vicious circle of MGD. Meibomian gland blockage, dropout and inflammation directly link the two vicious circles. MGD-associated tear film instability provides an entry point into the vicious circle of DED and leads to hyperosmolarity and inflammation, which are both a cause and consequence of DED. Here we propose a new pathophysiological scheme for MGD in order to better identify the pathological mechanisms involved and to allow more efficient targeting of therapeutics. Through better understanding of this scheme, MGD may gain true disease status rather than being viewed as a mere dysfunction. PMID:26781133

  16. Vertical head and trunk movement adaptations of sound horses trotting in a circle on a hard surface.

    PubMed

    Starke, Sandra D; Willems, Egbert; May, Stephen A; Pfau, Thilo

    2012-07-01

    Trotting a horse in circles is a standard and important part of the subjective equine lameness examination, yet objective data on this form of locomotion are sparse. The aim of this study was to investigate the effect of trotting in a circle on head and trunk movement symmetry. Vertical movements of the head, withers, os sacrum and left and right tuber coxae were measured using inertial sensors as 12 sound horses were trotted on a hard surface in a straight line and in a circle on both reins. Seven asymmetry measures and hip hike were calculated for each horse for at least nine strides of comparable stride duration across the three conditions (deviation on horse level ≤3.7% stride duration). Trotting in a circle introduced systematic changes to the movement pattern of all five body landmarks, affecting most asymmetry measures. On average the asymmetry magnitude was comparable for midline locations between reins and for the tuber coxae on opposite reins with few exceptions, although individual horses showed unsystematic differences between the two reins. The results from this study showed that the thresholds for objective discrimination between lame and non-lame horses will need adjustment on the circle due to the observed asymmetry bias. PMID:22104508

  17. Enhancing Students' Conceptual Understanding by Engaging Science Text with Reflective Writing as a Hermeneutical Circle

    NASA Astrophysics Data System (ADS)

    Kalman, Calvin S.

    2011-02-01

    Students can have great difficulty reading scientific texts and trying to cope with the professor in the classroom. Part of the reason for students' difficulties is that for a student taking a science gateway course the language, ontology and epistemology of science are akin to a foreign culture. There is thus an analogy between such a student and an anthropologist spending time among a native group in some remote part of the globe. This brings us naturally to the subject of hermeneutics. It is through language that we attempt to understand an alien culture. The hermeneutical circle involves the interplay between our construct of the unfamiliar with our own outlook that deepens with each pass. It can be argued that for novice students to acquire a full understanding of scientific texts, they also need to pursue a recurrent construction of their comprehension of scientific concepts. In this paper it is shown how an activity, reflective-writing, can enhance students' understanding of concepts in their textbook by getting students to approach text in the manner of a hermeneutical circle. This is illustrated using studies made at three post-secondary institutions.

  18. Child protection network and the intersector implementation of the circle of security as alternatives to medication☆

    PubMed Central

    Becker, Ana Laura Martins M.M.; de Souza, Paulo Haddad; de Oliveira, Mônica Martins; Paraguay, Nestor Luiz Bruzzi B.

    2014-01-01

    Objectives: To describe the clinical history of a child with aggressive behavior and recurring death-theme speech, and report the experience of the team of authors, who proposed an alternative to medication through the establishment of a protection network and the inter-sector implementation of the circle of security concept. Case description: A 5-year-old child has a violent and aggressive behavior at the daycare. The child was diagnosed by the healthcare center with depressive disorder and behavioral disorder, and was medicated with sertraline and risperidone. Side effects were observed, and the medications were discontinued. Despite several actions, such as talks, teamwork, psychological and psychiatric follow-up, the child's behavior remained unchanged. Remarks: A unique therapeutic project was developed by Universidade Estadual de Campinas' Medical School students in order to establish a connection between the entities responsible for the child's care (daycare center, healthcare center, and family). Thus, the team was able to develop a basic care protection network. The implementation of the inter-sector circle of security, as well as the communication and cooperation among the teams, produced very favorable results in this case. This initiative was shown to be a feasible and effective alternative to the use of medication for this child. PMID:25479857

  19. Optimisation of high bar circling technique for consistent performance of a triple piked somersault dismount.

    PubMed

    Hiley, Michael J; Yeadon, Maurice R

    2008-01-01

    The dismount from the high bar is one of the most spectacular skills performed in Men's Artistic Gymnastics. Hiley and Yeadon [2005. Maximal dismounts from high bar. Journal of Biomechanics 38, 2221-2227] optimised the technique in the backward giant circle prior to release using a computer simulation model to show that a gymnast could generate sufficient linear and angular momentum to perform a triple piked backward somersault dismount with a sufficiently large release window (the period of time during which the gymnast could release the bar and successfully complete the dismount). In the present study, it was found that when the timing of the actions at the hip and shoulder joints from the optimum simulation were perturbed by 30ms the resulting simulation could no longer meet the criteria for sufficient aerial rotation and release window. Since it is to be expected that a gymnast's technique can cope with small errors in timing for consistent performance, a requirement of robustness to timing perturbations should be included within the optimisation process. When the technique in the backward giant circle was optimised to be robust to 30ms perturbations, it was found that sufficient linear and angular momentum for a triple piked dismount could be achieved with a realistic release window. PMID:18402965

  20. Walt Disney World`s utility efficiency awards and environmental circles of excellence

    SciTech Connect

    Allen, P.J.; Kivler, W.B.

    1996-05-01

    This paper describes an innovative approach to energy conservation that has been started at WALT DISNEY WORLD. The program that was established was designed to heighten the awareness of energy usage in our Management and Cast Members, establish a method for recognizing and rewarding positive energy conservation efforts and, most importantly, keeping the effort simple and fun. Two programs work together to meet this goal: Utility Efficiency Awards and the Environmental Circles of Excellence. The Utility Efficiency Awards are given to the top areas that have demonstrated a reduction in utility consumption relative to the same period in prior years. More importantly, a report is generated that shows a best-to-worst ranking. Relying on the idea that {open_quotes}nobody wants to be on the bottom of the list{close_quotes}, conservation is enhanced by focusing attention on improving efficiency. To encourage direct cast member involvement in our environmental program, the Environmental Circles of Excellence were created. These groups, made up of hourly and salaried cast members, discuss their location`s environmental commitments, set goals and implement programs. This paper describes these initiatives in detail and presents some initial results that have heightened the awareness of energy conservation at WALT DISNEY WORLD.

  1. Linking Science Analysis with Observation Planning: A Full Circle Data Lifecycle

    NASA Technical Reports Server (NTRS)

    Grosvenor, Sandy; Jones, Jeremy; Koratkar, Anuradha; Li, Connie; Mackey, Jennifer; Neher, Ken; Wolf, Karl; Obenschain, Arthur F. (Technical Monitor)

    2001-01-01

    A clear goal of the Virtual Observatory (VO) is to enable new science through analysis of integrated astronomical archives. An additional and powerful possibility of the VO is to link and integrate these new analyses with planning of new observations. By providing tools that can be used for observation planning in the VO, the VO will allow the data lifecycle to come full circle: from theory to observations to data and back around to new theories and new observations. The Scientist's Expert Assistant (SEA) Simulation Facility (SSF) is working to combine the ability to access existing archives with the ability to model and visualize new observations. Integrating the two will allow astronomers to better use the integrated archives of the VO to plan and predict the success of potential new observations more efficiently, The full circle lifecycle enabled by SEA can allow astronomers to make substantial leaps in the quality of data and science returns on new observations. Our paper examines the exciting potential of integrating archival analysis with new observation planning, such as performing data calibration analysis on archival images and using that analysis to predict the success of new observations, or performing dynamic signal-to-noise analysis combining historical results with modeling of new instruments or targets. We will also describe how the development of the SSF is progressing and what have been its successes and challenges.

  2. Infraorbital Dark Circles: A Review of the Pathogenesis, Evaluation and Treatment

    PubMed Central

    Vrcek, Ivan; Ozgur, Omar; Nakra, Tanuj

    2016-01-01

    Infraorbital dark circles represent a common and multifactorial challenge in the world of aesthetic medicine and are the result of a variety of factors including deep facial anatomy, soft tissue changes, as well as contributions from the skin. A variety of treatment options exist, and a customised management strategy can be developed for the particular anatomic changes present. A literature search using MEDLINE and non-MEDLINE sources was performed utilising keywords including: ‘Dark circles’ ‘infraorbital dark circles’, ‘infraorbital pigment’, ‘under-eye circles’ and ‘lower eyelid bags’. A comprehensive review of the literature was performed and the data were assimilated with evidence from our practice. This review provides a detailed discussion of the aetiology, pathogenesis, evaluation and management of infraorbital dark circles. An understanding of the deep and superficial anatomy is crucial to the management of this complex entity. The armamentarium for treatment includes minimally invasive interventions such as makeup and cosmeceuticals, a variety of laser and chemical treatments, fillers and fat transfer, as well as more invasive surgical manoeuvres. PMID:27398005

  3. Self-organized vortices of circling self-propelled particles and curved active flagella.

    PubMed

    Yang, Yingzi; Qiu, Feng; Gompper, Gerhard

    2014-01-01

    Self-propelled pointlike particles move along circular trajectories when their translocation velocity is constant and the angular velocity related to their orientation vector is also constant. We investigate the collective behavior of ensembles of such circle swimmers by Brownian dynamics simulations. If the particles interact via a "velocity-trajectory coordination" rule within neighboring particles, a self-organized vortex pattern emerges. This vortex pattern is characterized by its particle-density correlation function Gρ, the density correlation function Gc of trajectory centers, and an order parameter S representing the degree of the aggregation of the particles. Here we systematically vary the system parameters, such as the particle density and the interaction range, in order to reveal the transition of the system from a light-vortex-dominated to heavy-vortex-dominated state, where vortices contain mainly a single and many self-propelled particles, respectively. We also study a semidilute solution of curved, sinusoidal-beating flagella, as an example of circling self-propelled particles with explicit propulsion mechanism and excluded-volume interactions. Our simulation results are compared with previous experimental results for the vortices in sea-urchin sperm solutions near a wall. The properties of the vortices in simulations and experiments are found to agree quantitatively. PMID:24580270

  4. Niche-Partitioning of Edaphic Microbial Communities in the Namib Desert Gravel Plain Fairy Circles

    PubMed Central

    Ramond, Jean-Baptiste; Pienaar, Annelize; Armstrong, Alacia; Seely, Mary; Cowan, Don A.

    2014-01-01

    Endemic to the Namib Desert, Fairy Circles (FCs) are vegetation-free circular patterns surrounded and delineated by grass species. Since first reported the 1970's, many theories have been proposed to explain their appearance, but none provide a fully satisfactory explanation of their origin(s) and/or causative agent(s). In this study, we have evaluated an early hypothesis stating that edaphic microorganisms could be involved in their formation and/or maintenance. Surface soils (0–5cm) from three different zones (FC center, FC margin and external, grass-covered soils) of five independent FCs were collected in April 2013 in the Namib Desert gravel plains. T-RFLP fingerprinting of the bacterial (16S rRNA gene) and fungal (ITS region) communities, in parallel with two-way crossed ANOSIM, showed that FC communities were significantly different to those of external control vegetated soil and that each FC was also characterized by significantly different communities. Intra-FC communities (margin and centre) presented higher variability than the controls. Together, these results provide clear evidence that edaphic microorganisms are involved in the Namib Desert FC phenomenon. However, we are, as yet, unable to confirm whether bacteria and/or fungi communities are responsible for the appearance and development of FCs or are a general consequence of the presence of the grass-free circles. PMID:25279514

  5. Self-organized vortices of circling self-propelled particles and curved active flagella

    NASA Astrophysics Data System (ADS)

    Yang, Yingzi; Qiu, Feng; Gompper, Gerhard

    2014-01-01

    Self-propelled pointlike particles move along circular trajectories when their translocation velocity is constant and the angular velocity related to their orientation vector is also constant. We investigate the collective behavior of ensembles of such circle swimmers by Brownian dynamics simulations. If the particles interact via a "velocity-trajectory coordination" rule within neighboring particles, a self-organized vortex pattern emerges. This vortex pattern is characterized by its particle-density correlation function Gρ, the density correlation function Gc of trajectory centers, and an order parameter S representing the degree of the aggregation of the particles. Here we systematically vary the system parameters, such as the particle density and the interaction range, in order to reveal the transition of the system from a light-vortex-dominated to heavy-vortex-dominated state, where vortices contain mainly a single and many self-propelled particles, respectively. We also study a semidilute solution of curved, sinusoidal-beating flagella, as an example of circling self-propelled particles with explicit propulsion mechanism and excluded-volume interactions. Our simulation results are compared with previous experimental results for the vortices in sea-urchin sperm solutions near a wall. The properties of the vortices in simulations and experiments are found to agree quantitatively.

  6. High-throughput genotyping of single nucleotide polymorphisms with rolling circle amplification

    PubMed Central

    Faruqi, A Fawad; Hosono, Seiyu; Driscoll, Mark D; Dean, Frank B; Alsmadi, Osama; Bandaru, Rajanikanta; Kumar, Gyanendra; Grimwade, Brian; Zong, Qiuling; Sun, Zhenyu; Du, Yuefen; Kingsmore, Stephen; Knott, Tim; Lasken, Roger S

    2001-01-01

    Background Single nucleotide polymorphisms (SNPs) are the foundation of powerful complex trait and pharmacogenomic analyses. The availability of large SNP databases, however, has emphasized a need for inexpensive SNP genotyping methods of commensurate simplicity, robustness, and scalability. We describe a solution-based, microtiter plate method for SNP genotyping of human genomic DNA. The method is based upon allele discrimination by ligation of open circle probes followed by rolling circle amplification of the signal using fluorescent primers. Only the probe with a 3' base complementary to the SNP is circularized by ligation. Results SNP scoring by ligation was optimized to a 100,000 fold discrimination against probe mismatched to the SNP. The assay was used to genotype 10 SNPs from a set of 192 genomic DNA samples in a high-throughput format. Assay directly from genomic DNA eliminates the need to preamplify the target as done for many other genotyping methods. The sensitivity of the assay was demonstrated by genotyping from 1 ng of genomic DNA. We demonstrate that the assay can detect a single molecule of the circularized probe. Conclusions Compatibility with homogeneous formats and the ability to assay small amounts of genomic DNA meets the exacting requirements of automated, high-throughput SNP scoring. PMID:11511324

  7. A CLIQUE algorithm using DNA computing techniques based on closed-circle DNA sequences.

    PubMed

    Zhang, Hongyan; Liu, Xiyu

    2011-07-01

    DNA computing has been applied in broad fields such as graph theory, finite state problems, and combinatorial problem. DNA computing approaches are more suitable used to solve many combinatorial problems because of the vast parallelism and high-density storage. The CLIQUE algorithm is one of the gird-based clustering techniques for spatial data. It is the combinatorial problem of the density cells. Therefore we utilize DNA computing using the closed-circle DNA sequences to execute the CLIQUE algorithm for the two-dimensional data. In our study, the process of clustering becomes a parallel bio-chemical reaction and the DNA sequences representing the marked cells can be combined to form a closed-circle DNA sequences. This strategy is a new application of DNA computing. Although the strategy is only for the two-dimensional data, it provides a new idea to consider the grids to be vertexes in a graph and transform the search problem into a combinatorial problem. PMID:21511001

  8. [Anesthetic circle system failure caused by a plastic film--a case report].

    PubMed

    Hara, Naoki; Tanaka, Tomohiro; Minami, Toshiaki

    2006-02-01

    A 44-year-old woman, ASA I, with breast cancer was scheduled for mastectomy. The anesthetic induction was performed by inhalation of 5% sevoflurane and 66% nitrous oxide in oxygen. After the loss of eyelash reflex assisted ventilation was initiated. At this point, the capnograph indicated inspired carbon dioxide tension of 18mmHg. Anesthetic machine check was soon carried out again. A visual check of non-return valves detected a plastic film, 18 x 21mm large, caught in the expiratory valve. This plastic film impaired complete occlusion of the orifice for the expiratory gas flow. As a result, the patient was rebreathing carbon dioxide. After removing it, the wave form of the capnograph was normalized and end-tidal carbon dioxide tension decreased immediately from 45mmHg to 33mmHg. As we did not detect any foreign matters at the non-return valves on anesthetic machine check before use, the plastic film might have already existed in the disposable corrugated tube before use. The capnograph is a useful device for detecting anesthetic circle system failure in such a case. It is important that the patients' airway is separated from the anesthetic circle system through the use of a filter to prevent foreign matter from being inhaled. PMID:16491902

  9. Replication of avocado sunblotch viroid: evidence for a symmetric pathway with two rolling circles and hammerhead ribozyme processing.

    PubMed Central

    Daròs, J A; Marcos, J F; Hernández, C; Flores, R

    1994-01-01

    The structure of a series of RNAs extracted from avocado infected by the 247-nt avocado sunblotch viroid (ASBVd) was investigated. The identification of multistranded complexes containing circular ASBVd RNAs of (+) and (-) polarity suggests that replication of ASBVd proceeds through a symmetric pathway with two rolling circles where these two circular RNAs are the templates. This is in contrast to the replication of potato spindle tuber viroid and probably of most of its related viroids, which proceeds via an asymmetric pathway where circular (+)-strand and linear multimeric (-)-strand RNAs are the two templates. Linear (+) and (-) ASBVd RNAs of subgenomic length (137 nt and about 148 nt, respectively) and one linear (+)-strand ASBVd RNA of supragenomic length (383-384 nt) were also found in viroid-infected tissue. The two linear (+)-strand RNAs have the same 5'- and 3'-terminal sequences, with the supragenomic species being a fusion product of the monomeric and subgenomic (+)-strand ASBVd RNAs. The 3' termini of these two (+)-strand molecules, which at least in the subgenomic RNA has an extra nontemplate cytidylate residue, could represent sites of either premature termination of the (+)-strands or specific initiation of the (-)-strands. The 5' termini of sub- and supragenomic (+)-strand and the 5' terminus of the subgenomic (-)-strand ASBVd RNA are identical to those produced in the in vitro self-cleavage reactions of (+) and (-) dimeric ASBVd RNAs, respectively. These observations strongly suggest that the hammerhead structures which mediate the in vitro self-cleavage reactions are also operative in vivo. Images Fig. 1 Fig. 3 Fig. 4 Fig. 5 PMID:7809126

  10. The influence of scan mode and circle fitting on tree stem detection, stem diameter and volume extraction from terrestrial laser scans

    NASA Astrophysics Data System (ADS)

    Pueschel, Pyare; Newnham, Glenn; Rock, Gilles; Udelhoven, Thomas; Werner, Willy; Hill, Joachim

    2013-03-01

    Terrestrial laser scanning (TLS) has been used to estimate a number of biophysical and structural vegetation parameters. Of these stem diameter is a primary input to traditional forest inventory. While many experimental studies have confirmed the potential for TLS to successfully extract stem diameter, the estimation accuracies differ strongly for these studies - due to differences in experimental design, data processing and test plot characteristics. In order to provide consistency and maximize estimation accuracy, a systematic study into the impact of these variables is required. To contribute to such an approach, 12 scans were acquired with a FARO photon 120 at two test plots (Beech, Douglas fir) to assess the effects of scan mode and circle fitting on the extraction of stem diameter and volume. An automated tree stem detection algorithm based on the range images of single scans was developed and applied to the data. Extraction of stem diameter was achieved by slicing the point cloud and fitting circles to the slices using three different algorithms (Lemen, Pratt and Taubin), resulting in diameter profiles for each detected tree. Diameter at breast height (DBH) was determined using both the single value for the diameter fitted at the nominal breast height and by a linear fit of the stem diameter vertical profile. The latter is intended to reduce the influence of outliers and errors in the ground level determination. TLS-extracted DBH was compared to tape-measured DBH. Results show that tree stems with an unobstructed view to the scanner can be successfully extracted automatically from range images of the TLS data with detection rates of 94% for Beech and 96% for Douglas fir. If occlusion of trees is accounted for stem detection rates decrease to 85% (Beech) and 84% (Douglas fir). As far as the DBH estimation is concerned, both DBH extraction methods yield estimates which agree with reference measurements, however, the linear fit based approach proved to be more

  11. Practical Environmental Education and Local Contribution in the Environmental Science Laboratory Circle in the College of Science and Technology in Nihon University

    NASA Astrophysics Data System (ADS)

    Taniai, Tetsuyuki; Ito, Ken-Ichi; Sakamaki, Hiroshi

    In this paper, we presented a method and knowledge about a practical and project management education and local contribution obtained through the student activities of “Environmental science laboratory circle in the College of Science and technology in Nihon University” from 1991 to 2001. In this circle, four major projects were acted such as research, protection, clean up and enlightenment projects. Due to some problems from inside or outside of this circle, this circle projects have been stopped. The diffusion and popularization of the internet technology will help to resolve some of these problems.

  12. The Boston-area HASWIC Research Circle: an innovative participatory method for coloring in the picture of a special work environment.

    PubMed

    Moir, Susan; Azaroff, Lenore S

    2007-01-01

    Recent qualitative studies have investigated some of the hazards affecting women in non-traditional trades such as construction. However, one-time interactions among researcher participants, and between researchers and participants, in standard settings such as focus groups and interviews, cannot provide the time, space, and relationships to fully explore tradeswomen's in-depth knowledge of their work environment. This study applied a Scandinavian method called the Research Circle to convene a group of experienced women construction workers repeatedly over a period of two years so they could collaborate with researchers in explaining workplace issues. The results both validated and expanded upon previous findings about health and safety for women in construction, including gender discrimination, lack of access to sanitary facilities, retaliation for reporting hazards and injuries, and inadequate training and equipment. Especially important, findings illustrate some of the complex hierarchical social structures involved in both female and male construction workers responding to hazardous conditions. PMID:17434864

  13. Are we indeed what we eat? Street food consumption in the Market Circle area of Takoradi, Ghana.

    PubMed

    Hiamey, Stephen Edem; Amuquandoh, Francis Eric; Boison, Grace Aba

    2013-01-01

    The paper examines street foods consumption in the Market Circle of Sekondi-Takoradi, Ghana. The data used for the study were obtained from individuals who were either purchasing or consuming street foods in the Market Circle in August of 2011. The results revealed that the average consumer makes use of street foods six times in a week and there was a penchant for carbohydrate based foods over other types of street foods. Reasons including cost saving, convenience and eating on credit were noted to underlie the consumption of street foods in the area. Based on the findings, it was concluded that the high consumption of street foods in the Market Circle was for reasons other than nutrition and health. PMID:26341743

  14. Generic Equations for Constructing Smooth Paths Along Circles and Tangent Lines With Application to Airport Ground Paths

    NASA Technical Reports Server (NTRS)

    Barker, L. Keith

    1998-01-01

    The primary purpose of this publication is to develop a mathematical model to describe smooth paths along any combination of circles and tangent lines. Two consecutive circles in a path are either tangent (externally or internally) or they appear on the same (lateral) or opposite (transverse) sides of a connecting tangent line. A path may start or end on either a segment or circle. The approach is to use mathematics common to robotics to design the path as a multilink manipulator. This approach allows a hierarchical view of the problem and keeps the notation manageable. A user simply specifies a few parameters to configure a path. Necessary and sufficient conditions automatically ensure the consistency of the inputs for a smooth path. Two example runway exit paths are given, and an angle to go assists in knowing when to switch from one path element to the next.

  15. T cell receptor excision circle assessment of thymopoiesis in aging mice.

    PubMed

    Sempowski, Gregory D; Gooding, Maria E; Liao, H X; Le, Phong T; Haynes, Barton F

    2002-03-01

    Signal joint T cell receptor delta (TCRD) excision circles (TRECs) are episomal DNA circles generated by the DNA recombination process that is used by T lymphocytes to produce antigen-specific alpha/beta T cell receptors. Measurement of TRECs in thymocytes and peripheral blood T cells has been used to study thymus output in chickens and humans. We have developed a real-time quantitative-PCR assay for the specific detection and quantification of mouse TCRD episomal DNA circles excised from the TCRA locus during TCRA gene rearrangement (mTRECs). We found that the mouse TCRD TRECs detected with this assay were predominantly in naïve phenotype CD4(+) and CD8(+) T cells. In a series of aged mice (range 6-90-week-old) we determined the absolute number of thymocytes and the number of molecules of mTRECs/100,000 thymocytes. We found that the absolute number of thymocytes dramatically decreased with age (P<0.05) and that molecules of mTREC/100,000 thymocytes also declined with mouse age (P<0.05). Splenocytes were isolated from aging mice and the frequency of naïve phenotype CD4 and CD8 cells determined. There was a significant drop in both CD4 and CD8 naïve peripheral T cells in the aged mice over time. mTREC analysis in purified CD4(+) and CD8(+) splenocytes demonstrated a constant level of mTRECs in the CD4 compartment until age 90 weeks, while the mTRECs in the CD8 compartment fell with age (P<0.05). By combining the mouse TREC assay with T cell phenotypic analysis, we demonstrated that IL-7 administration to young mice induced both increased thymopoiesis and peripheral T cell proliferation. In contrast, IL-7 treatment of aged mice did not augment thymopoiesis, nor induce expansion of splenic T cells. Thus, thymus output continues throughout murine adult life, and the thymic atrophy of aging in mice is not reversed by administration of IL-7. PMID:11922942

  16. A multiloop generalization of the circle criterion for stability margin analysis

    NASA Technical Reports Server (NTRS)

    Safonov, M. G.; Athans, M.

    1979-01-01

    In order to provide a theoretical tool suited for characterizing the stability margins of multiloop feedback systems, multiloop input-output stability results generalizing the circle stability criterion are considered. Generalized conic sectors with 'centers' and 'radii' determined by linear dynamical operators are employed to specify the stability margins as a frequency dependent convex set of modeling errors (including nonlinearities, gain variations and phase variations) which the system must be able to tolerate in each feedback loop without instability. The resulting stability criterion gives sufficient conditions for closed loop stability in the presence of frequency dependent modeling errors, even when the modeling errors occur simultaneously in all loops. The stability conditions yield an easily interpreted scalar measure of the amount by which a multiloop system exceeds, or falls short of, its stability margin specifications.

  17. Full-Circle Color Panorama of Phoenix Landing Site on Northern Mars, Vertical Projection

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This view combines more than 400 images taken during the first several weeks after NASA's Phoenix Mars Lander arrived on an arctic plain at 68.22 degrees north latitude, 234.25 degrees east longitude on Mars.

    The full-circle panorama in approximately true color shows the polygonal patterning of ground in the landing area, similar to patterns in permafrost areas on Earth. North is toward the top. Trenches where Phoenix's robotic arm has been exposing subsurface material are visible just north of the lander.

    This view comprises more than 100 different camera pointings, with images taken through three different filters at each pointing. It is presented here as a vertical projection.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  18. Fabrication of DNA Polymer Brush Arrays by Destructive Micropatterning and Rolling-Circle Amplification

    PubMed Central

    Barbee, Kristopher D.; Chandrangsu, Matt; Huang, Xiaohua

    2011-01-01

    A method for fabricating DNA polymer brush arrays using photolithography and plasma etching followed by solid-phase enzymatic DNA amplification is reported. After attaching oligonucleotide primers to the surface of a glass coverslip, a thin layer of photoresist is spin-coated on the glass and patterned via photolithography to generate an array of posts in the resist. An oxygen-based plasma is then used to destroy the exposed oligonucleotide primers. The glass coverslip with the primer array is assembled into a microfluidic chip and DNA polymer brushes are synthesized on the oligonucleotide array by rolling-circle DNA amplification. We have demonstrated that the linear polymers can be rapidly synthesized in situ with a high degree of control over their density and length. PMID:21305694

  19. A multiloop generalization of the circle criterion for stability margin analysis

    NASA Technical Reports Server (NTRS)

    Safonov, M. G.; Athans, M.

    1981-01-01

    In order to provide a theoretical tool well suited for use in characterizing the stability margins (e.g., gain and phase margins) of multiloop feedback systems, multiloop input-output stability results generalizing the circle stability criterion are considered. Generalized conic sectors with 'centers' and 'radii' determined by linear dynamical operators are employed to enable an engineer to specify the stability margins which he desires as a frequency-dependent convex set of modeling errors (including nonlinearities, gain variations, and phase variations) which the system must be able to tolerate in each feedback loop without instability. The resulting stability criterion gives sufficient conditions for closed-loop stability in the presence of such frequency-dependent modeling errors, even when the modeling errors occur simultaneously in all loops.

  20. Lessons from Five States: Public Sector Use of Washington Circle Performance Measures

    PubMed Central

    Garnick, Deborah W.; Lee, Margaret T.; Horgan, Constance; Acevedo, Andrea; Botticelli, Michael; Clark, Spencer; Davis, Steven; Gallati, Robert; Haberlin, Karin; Hanchett, Andrew; Lambert–Wacey, Dawn; Leeper, Tracy; Siemianowski, James; Tikoo, Minakshi

    2011-01-01

    Five states (Connecticut, Massachusetts, New York, North Carolina, and Oklahoma) have incorporated Washington Circle (WC) substance abuse performance measures in various ways into their quality improvement strategies. In this paper we focus on what other states and local providers might learn from these states’ experiences as they consider using WC performance measures. Using a case study approach, we report that the use of WC measures differs across these five states, although there are important common themes required for adoption and sustainability of performance measures which include: leadership, evaluation of specification and use of measures over time, state-specific adaptation of the WC measure specifications, collaboration with consultants and partners, inclusion of WC measures in the context of other initiatives, reporting to providers and the public, and data and resource requirements. As additional states adopt some of the WC measures, or adopt other performance measurement approaches, these states’ experiences could help them to develop implementations based on their particular needs. PMID:21257282