WorldWideScience

Sample records for single heterochromatin boundary

  1. Heterochromatin Reorganization during Early Mouse Development Requires a Single-Stranded Noncoding Transcript

    Directory of Open Access Journals (Sweden)

    Miguel Casanova

    2013-09-01

    Full Text Available The equalization of pericentric heterochromatin from distinct parental origins following fertilization is essential for genome function and development. The recent implication of noncoding transcripts in this process raises questions regarding the connection between RNA and the nuclear organization of distinct chromatin environments. Our study addresses the interrelationship between replication and transcription of the two parental pericentric heterochromatin (PHC domains and their reorganization during early embryonic development. We demonstrate that the replication of PHC is dispensable for its clustering at the late two-cell stage. In contrast, using parthenogenetic embryos, we show that pericentric transcripts are essential for this reorganization independent of the chromatin marks associated with the PHC domains. Finally, our discovery that only reverse pericentric transcripts are required for both the nuclear reorganization of PHC and development beyond the two-cell stage challenges current views on heterochromatin organization.

  2. Regulation of Neurospora Catalase-3 by global heterochromatin formation and its proximal heterochromatin region.

    Science.gov (United States)

    Wang, Yajun; Dong, Qing; Ding, Zhaolan; Gai, Kexin; Han, Xiaoyun; Kaleri, Farah Naz; He, Qun; Wang, Ying

    2016-10-01

    Catalase-3 (CAT-3) constitutes the main catalase activity in growing hyphae of Neurospora crassa, and its activity increases during exponential growth or is induced under different stress conditions. Although extensive progress has been made to identify catalase regulators, the regulation mechanism of CAT-3 at the chromatin level still remains unclear. Here, we aim at investigating the molecular regulation mechanisms of cat-3 at the chromatin level. We found that CAT-3 protein levels increased in mutants defective in proper global heterochromatin formation. Bioinformatics analysis identified a 5-kb AT-rich sequence adjacent to the cat-3 promoter as a heterochromatin region because of its enrichment of H3K9me3 and HP1. Expression of CAT-3 was induced by H 2 O 2 treatment in wild-type and such change occurred along with the accumulation of histone H3 acetylation at 5-kb heterochromatin boundaries and cat-3 locus, but without alteration of its H3K9me3 repressive modification. Moreover, disruption of 5-kb heterochromatin region results in elevated cat-3 expression, and higher levels of cat-3 expression were promoted by the combination with global heterochromatin defective mutants. Interestingly, the molecular weight and activity bands of CAT-3 protein are different in heterochromatin defective mutants compared with those in wild-type, suggesting that its N-terminal processing and modification may be altered. Our study indicates that the local chromatin structure creates a heterochromatin repressive environment to repress nearby gene expression. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Treating the Changing Single Parent Family: A Return to Boundaries.

    Science.gov (United States)

    Greif, Geoffrey L.

    1996-01-01

    Examines the concept of boundaries--drawing of emotional lines between family subsystems, and between "family" and the outside world--in assessment and intervention with single parent families. Argues that clear, flexible boundaries are needed for healthy family functioning; that coalitions, rigid or unclear boundaries, and triangulation…

  4. Local chromatin structure of heterochromatin regulates repeated DNA stability, nucleolus structure, and genome integrity

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Jamy C. [Univ. of California, Berkeley, CA (United States)

    2007-01-01

    Heterochromatin constitutes a significant portion of the genome in higher eukaryotes; approximately 30% in Drosophila and human. Heterochromatin contains a high repeat DNA content and a low density of protein-encoding genes. In contrast, euchromatin is composed mostly of unique sequences and contains the majority of single-copy genes. Genetic and cytological studies demonstrated that heterochromatin exhibits regulatory roles in chromosome organization, centromere function and telomere protection. As an epigenetically regulated structure, heterochromatin formation is not defined by any DNA sequence consensus. Heterochromatin is characterized by its association with nucleosomes containing methylated-lysine 9 of histone H3 (H3K9me), heterochromatin protein 1 (HP1) that binds H3K9me, and Su(var)3-9, which methylates H3K9 and binds HP1. Heterochromatin formation and functions are influenced by HP1, Su(var)3-9, and the RNA interference (RNAi) pathway. My thesis project investigates how heterochromatin formation and function impact nuclear architecture, repeated DNA organization, and genome stability in Drosophila melanogaster. H3K9me-based chromatin reduces extrachromosomal DNA formation; most likely by restricting the access of repair machineries to repeated DNAs. Reducing extrachromosomal ribosomal DNA stabilizes rDNA repeats and the nucleolus structure. H3K9me-based chromatin also inhibits DNA damage in heterochromatin. Cells with compromised heterochromatin structure, due to Su(var)3-9 or dcr-2 (a component of the RNAi pathway) mutations, display severe DNA damage in heterochromatin compared to wild type. In these mutant cells, accumulated DNA damage leads to chromosomal defects such as translocations, defective DNA repair response, and activation of the G2-M DNA repair and mitotic checkpoints that ensure cellular and animal viability. My thesis research suggests that DNA replication, repair, and recombination mechanisms in heterochromatin differ from those in

  5. Bandgap tunability at single-layer molybdenum disulphide grain boundaries

    KAUST Repository

    Huang, Yu Li

    2015-02-17

    Two-dimensional transition metal dichalcogenides have emerged as a new class of semiconductor materials with novel electronic and optical properties of interest to future nanoelectronics technology. Single-layer molybdenum disulphide, which represents a prototype two-dimensional transition metal dichalcogenide, has an electronic bandgap that increases with decreasing layer thickness. Using high-resolution scanning tunnelling microscopy and spectroscopy, we measure the apparent quasiparticle energy gap to be 2.40±0.05 eV for single-layer, 2.10±0.05 eV for bilayer and 1.75±0.05 eV for trilayer molybdenum disulphide, which were directly grown on a graphite substrate by chemical vapour deposition method. More interestingly, we report an unexpected bandgap tunability (as large as 0.85±0.05 eV) with distance from the grain boundary in single-layer molybdenum disulphide, which also depends on the grain misorientation angle. This work opens up new possibilities for flexible electronic and optoelectronic devices with tunable bandgaps that utilize both the control of two-dimensional layer thickness and the grain boundary engineering.

  6. Vibration modes of a single plate with general boundary conditions

    Directory of Open Access Journals (Sweden)

    Phamová L.

    2016-06-01

    Full Text Available This paper deals with free flexural vibration modes and natural frequencies of a thin plate with general boundary conditions — a simply supported plate connected to its surroundings with torsional springs. Vibration modes were derived on the basis of the Rajalingham, Bhat and Xistris approach. This approach was originally used for a clamped thin plate, so its adaptation was needed. The plate vibration function was usually expressed as a single partial differential equation. This partial differential equation was transformed into two ordinary differential equations that can be solved in the simpler way. Theoretical background of the computations is briefly described. Vibration modes of the supported plate with torsional springs are presented graphically and numerically for three different values of stiffness of torsional springs.

  7. Genome mapping and characterization of the Anopheles gambiae heterochromatin

    Directory of Open Access Journals (Sweden)

    Sharakhova Maria V

    2010-08-01

    Full Text Available Abstract Background Heterochromatin plays an important role in chromosome function and gene regulation. Despite the availability of polytene chromosomes and genome sequence, the heterochromatin of the major malaria vector Anopheles gambiae has not been mapped and characterized. Results To determine the extent of heterochromatin within the An. gambiae genome, genes were physically mapped to the euchromatin-heterochromatin transition zone of polytene chromosomes. The study found that a minimum of 232 genes reside in 16.6 Mb of mapped heterochromatin. Gene ontology analysis revealed that heterochromatin is enriched in genes with DNA-binding and regulatory activities. Immunostaining of the An. gambiae chromosomes with antibodies against Drosophila melanogaster heterochromatin protein 1 (HP1 and the nuclear envelope protein lamin Dm0 identified the major invariable sites of the proteins' localization in all regions of pericentric heterochromatin, diffuse intercalary heterochromatin, and euchromatic region 9C of the 2R arm, but not in the compact intercalary heterochromatin. To better understand the molecular differences among chromatin types, novel Bayesian statistical models were developed to analyze genome features. The study found that heterochromatin and euchromatin differ in gene density and the coverage of retroelements and segmental duplications. The pericentric heterochromatin had the highest coverage of retroelements and tandem repeats, while intercalary heterochromatin was enriched with segmental duplications. We also provide evidence that the diffuse intercalary heterochromatin has a higher coverage of DNA transposable elements, minisatellites, and satellites than does the compact intercalary heterochromatin. The investigation of 42-Mb assembly of unmapped genomic scaffolds showed that it has molecular characteristics similar to cytologically mapped heterochromatin. Conclusions Our results demonstrate that Anopheles polytene chromosomes

  8. Silencing markers are retained on pericentric heterochromatin during murine primordial germ cell development.

    Science.gov (United States)

    Magaraki, Aristea; van der Heijden, Godfried; Sleddens-Linkels, Esther; Magarakis, Leonidas; van Cappellen, Wiggert A; Peters, Antoine H F M; Gribnau, Joost; Baarends, Willy M; Eijpe, Maureen

    2017-01-01

    In the nuclei of most mammalian cells, pericentric heterochromatin is characterized by DNA methylation, histone modifications such as H3K9me3 and H4K20me3, and specific binding proteins like heterochromatin-binding protein 1 isoforms (HP1 isoforms). Maintenance of this specialized chromatin structure is of great importance for genome integrity and for the controlled repression of the repetitive elements within the pericentric DNA sequence. Here we have studied histone modifications at pericentric heterochromatin during primordial germ cell (PGC) development using different fixation conditions and fluorescent immunohistochemical and immunocytochemical protocols. We observed that pericentric heterochromatin marks, such as H3K9me3, H4K20me3, and HP1 isoforms, were retained on pericentric heterochromatin throughout PGC development. However, the observed immunostaining patterns varied, depending on the fixation method, explaining previous findings of a general loss of pericentric heterochromatic features in PGCs. Also, in contrast to the general clustering of multiple pericentric regions and associated centromeres in DAPI-dense regions in somatic cells, the pericentric regions of PGCs were more frequently organized as individual entities. We also observed a transient enrichment of the chromatin remodeler ATRX in pericentric regions in embryonic day 11.5 (E11.5) PGCs. At this stage, a similar and low level of major satellite repeat RNA transcription was detected in both PGCs and somatic cells. These results indicate that in pericentric heterochromatin of mouse PGCs, only minor reductions in levels of some chromatin-associated proteins occur, in association with a transient increase in ATRX, between E11.5 and E13.5. These pericentric heterochromatin regions more frequently contain only a single centromere in PGCs compared to the surrounding soma, indicating a difference in overall organization, but there is no de-repression of major satellite transcription.

  9. Genetic and bioinformatic analysis of 41C and the 2R heterochromatin of Drosophila melanogaster: a window on the heterochromatin-euchromatin junction.

    OpenAIRE

    Myster, Steven H; Wang, Fei; Cavallo, Robert; Christian, Whitney; Bhotika, Seema; Anderson, Charles T; Peifer, Mark

    2004-01-01

    Genomic sequences provide powerful new tools in genetic analysis, making it possible to combine classical genetics with genomics to characterize the genes in a particular chromosome region. These approaches have been applied successfully to the euchromatin, but analysis of the heterochromatin has lagged somewhat behind. We describe a combined genetic and bioinformatics approach to the base of the right arm of the Drosophila melanogaster second chromosome, at the boundary between pericentric h...

  10. Misorientation related microstructure at the grain boundary in a nickel-based single crystal superalloy

    International Nuclear Information System (INIS)

    Huang, Ming; Zhuo, Longchao; Liu, Zhanli; Lu, Xiaogang; Shi, Zhenxue; Li, Jiarong; Zhu, Jing

    2015-01-01

    The mechanical properties of nickel-based single crystal superalloys deteriorate with increasing misorientation, thus the finished product rate of the casting of single crystal turbine airfoils may be reduced due to the formation of grain boundaries especially when the misorientation angle exceeds to some extent. To this day, evolution of the microstructures at the grain boundaries with misorientation and the relationship between the microstructures and the mechanical properties are still unclear. In this work a detailed characterization of the misorientation related microstructure at the grain boundary in DD6 single crystal superalloy has been carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques; the elemental distribution at the grain boundaries has been analyzed by energy dispersive (EDS) X-ray mapping; and the effect of precipitation of μ phases at the grain boundary on the mechanical property has been evaluated by finite element calculation. It is shown that the proportion of γ phase at the grain boundaries decreases, while the proportion of γ′ phase at the grain boundaries increases with increasing misorientation; the μ phase is precipitated at the grain boundaries when the misorientation angle exceeds about 10° and thus it could lead to a dramatic deterioration of the mechanical properties, as well as that the enrichment of Re and W gradually disappears as the misorientation angle increases. All these factors may result in the degradation of the mechanical properties at the grain boundaries as the misorientation increases. Furthermore, the finite element calculation confirms that precipitation of μ phases at the grain boundary is responsible for the significant deterioration of the mechanical properties when the misorientation exceeds about 10°. This work provides a physical imaging of the microstructure for understanding the relationship between the mechanical properties and the misorientation

  11. Centromeric heterochromatin: the primordial segregation machine.

    Science.gov (United States)

    Bloom, Kerry S

    2014-01-01

    Centromeres are specialized domains of heterochromatin that provide the foundation for the kinetochore. Centromeric heterochromatin is characterized by specific histone modifications, a centromere-specific histone H3 variant (CENP-A), and the enrichment of cohesin, condensin, and topoisomerase II. Centromere DNA varies orders of magnitude in size from 125 bp (budding yeast) to several megabases (human). In metaphase, sister kinetochores on the surface of replicated chromosomes face away from each other, where they establish microtubule attachment and bi-orientation. Despite the disparity in centromere size, the distance between separated sister kinetochores is remarkably conserved (approximately 1 μm) throughout phylogeny. The centromere functions as a molecular spring that resists microtubule-based extensional forces in mitosis. This review explores the physical properties of DNA in order to understand how the molecular spring is built and how it contributes to the fidelity of chromosome segregation.

  12. RNAi and heterochromatin repress centromeric meiotic recombination

    DEFF Research Database (Denmark)

    Ellermeier, Chad; Higuchi, Emily C; Phadnis, Naina

    2010-01-01

    to genetic disabilities, including birth defects. The basis by which centromeric meiotic recombination is repressed has been largely unknown. We report here that, in fission yeast, RNAi functions and Clr4-Rik1 (histone H3 lysine 9 methyltransferase) are required for repression of centromeric recombination....... Surprisingly, one mutant derepressed for recombination in the heterochromatic mating-type region during meiosis and several mutants derepressed for centromeric gene expression during mitotic growth are not derepressed for centromeric recombination during meiosis. These results reveal a complex relation between...... types of repression by heterochromatin. Our results also reveal a previously undemonstrated role for RNAi and heterochromatin in the repression of meiotic centromeric recombination and, potentially, in the prevention of birth defects by maintenance of proper chromosome segregation during meiosis....

  13. Effects of microscopic boundary conditions on plastic deformations of small-sized single crystals

    DEFF Research Database (Denmark)

    Kuroda, Mitsutoshi; Tvergaard, Viggo

    2009-01-01

    The finite deformation version of the higher-order gradient crystal plasticity model proposed by the authors is applied to solve plane strain boundary value problems, in order to obtain an understanding of the effect of the higher-order boundary conditions. Numerical solutions are carried out...... for uniaxial plane strain compression of a single crystal block and for uniform pure bending of a single crystal foil. The compressed block has loading surfaces that are penetrable or impenetrable to dislocations. This allows for a study of the two types of higher-order boundaries available, and a significant...

  14. Guanine quadruplex structures localize to heterochromatin.

    Science.gov (United States)

    Hoffmann, Roland F; Moshkin, Yuri M; Mouton, Stijn; Grzeschik, Nicola A; Kalicharan, Ruby D; Kuipers, Jeroen; Wolters, Anouk H G; Nishida, Kazuki; Romashchenko, Aleksander V; Postberg, Jan; Lipps, Hans; Berezikov, Eugene; Sibon, Ody C M; Giepmans, Ben N G; Lansdorp, Peter M

    2016-01-08

    Increasing amounts of data support a role for guanine quadruplex (G4) DNA and RNA structures in various cellular processes. We stained different organisms with monoclonal antibody 1H6 specific for G4 DNA. Strikingly, immuno-electron microscopy showed exquisite specificity for heterochromatin. Polytene chromosomes from Drosophila salivary glands showed bands that co-localized with heterochromatin proteins HP1 and the SNF2 domain-containing protein SUUR. Staining was retained in SUUR knock-out mutants but lost upon overexpression of SUUR. Somatic cells in Macrostomum lignano were strongly labeled, but pluripotent stem cells labeled weakly. Similarly, germline stem cells in Drosophila ovaries were weakly labeled compared to most other cells. The unexpected presence of G4 structures in heterochromatin and the difference in G4 staining between somatic cells and stem cells with germline DNA in ciliates, flatworms, flies and mammals point to a conserved role for G4 structures in nuclear organization and cellular differentiation. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  15. Molecular landscape of modified histones in Drosophila heterochromatic genes and euchromatin-heterochromatin transition zones.

    Directory of Open Access Journals (Sweden)

    Jiro C Yasuhara

    2008-01-01

    Full Text Available Constitutive heterochromatin is enriched in repetitive sequences and histone H3-methylated-at-lysine 9. Both components contribute to heterochromatin's ability to silence euchromatic genes. However, heterochromatin also harbors hundreds of expressed genes in organisms such as Drosophila. Recent studies have provided a detailed picture of sequence organization of D. melanogaster heterochromatin, but how histone modifications are associated with heterochromatic sequences at high resolution has not been described. Here, distributions of modified histones in the vicinity of heterochromatic genes of normal embryos and embryos homozygous for a chromosome rearrangement were characterized using chromatin immunoprecipitation and genome tiling arrays. We found that H3-di-methylated-at-lysine 9 (H3K9me2 was depleted at the 5' ends but enriched throughout transcribed regions of heterochromatic genes. The profile was distinct from that of euchromatic genes and suggests that heterochromatic genes are integrated into, rather than insulated from, the H3K9me2-enriched domain. Moreover, the profile was only subtly affected by a Su(var3-9 null mutation, implicating a histone methyltransferase other than SU(VAR3-9 as responsible for most H3K9me2 associated with heterochromatic genes in embryos. On a chromosomal scale, we observed a sharp transition to the H3K9me2 domain, which coincided with increased retrotransposon density in the euchromatin-heterochromatin (eu-het transition zones on the long chromosome arms. Thus, a certain density of retrotransposons, rather than specific boundary elements, may demarcate Drosophila pericentric heterochromatin. We also demonstrate that a chromosome rearrangement that created a new eu-het junction altered H3K9me2 distribution and induced new euchromatic sites of enrichment as far as several megabases away from the breakpoint. Taken together, the findings argue against simple classification of H3K9me as the definitive signature

  16. Pressure estimation from single-snapshot tomographic PIV in a turbulent boundary layer

    NARCIS (Netherlands)

    Schneiders, J.F.G.; Pröbsting, S.; Dwight, R.P.; Van Oudheusden, B.W.; Scarano, F.

    2016-01-01

    A method is proposed to determine the instantaneous pressure field from a single tomographic PIV velocity snapshot and is applied to a flat-plate turbulent boundary layer. The main concept behind the single-snapshot pressure evaluation method is to approximate the flow acceleration using the

  17. Inclusion estimation from a single electrostatic boundary measurement

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Knudsen, Kim

    2013-01-01

    We present a numerical method for the detection and estimation of perfectly conducting inclusions in conducting homogeneous host media in . The estimation is based on the evaluation of an indicator function that depends on a single pair of Cauchy data (electric potential and current) given...... in a natural physical interpretation. The method is implemented numerically, tested on different example problems and compared to a decomposition approach based on the method of fundamental solutions. The method shows promising results and seems robust to noisy, low sampling-frequency data....

  18. Containing psychotic patients with fragile boundaries: a single-session group case study.

    Science.gov (United States)

    Lavarenne, Anaïs; Segal, Emily; Sigman, Maxine

    2013-01-01

    This case study describes a single group psychotherapy session of six individuals suffering from schizophrenia or schizoaffective illness, which was characterized by numerous manifestations of fragile Ego boundaries. Based on these illustrations of fragile Ego boundaries, we explore some of the group's core therapeutic actions against psychosis. We discuss how the group (1) provides access to a structuring auxiliary Ego, (2) acts as a containing object by establishing firm boundaries and by mentalizing patients' psychotic productions, and (3) may become a solid object representation introjected by individuals wrestling with porous Ego boundaries and a poor sense of self. We conclude that, in addition to the known role of group therapy in increasing mature defenses, developing insight and providing social support, the group promotes healthier Ego boundaries, and eventually improves self-differentiation, and also tolerance to interpersonal proximity. This case study clarifies group therapy dynamics with individuals suffering from psychosis.

  19. Heterochromatin and the molecular mechanisms of 'parent-of-origin ...

    Indian Academy of Sciences (India)

    Permanent link: http://www.ias.ac.in/article/fulltext/jbsc/041/04/0759-0786. Keywords. Epigenetics; genomic imprinting; heterochromatin; HP1; KRAB-ZFP. Abstract. Twenty five years ago it was proposed that conserved components of constitutive heterochromatin assemble heterochromatinlikecomplexes in euchromatin and ...

  20. Direct observation of liquid-like behavior of a single Au grain boundary.

    Science.gov (United States)

    Casillas, Gilberto; Ponce, Arturo; Velázquez-Salazar, J Jesús; José-Yacamán, Miguel

    2013-07-21

    Behavior of matter at the nanoscale differs from that of the bulk due to confinement and surface effects. Here, we report a direct observation of liquid-like behavior of a single grain boundary formed by cold-welding Au nanoparticles, 40 nm in size, by mechanical manipulation in situ TEM. The grain boundary rotates almost freely due to the free surfaces and can rotate about 90 degrees. The grain boundary sustains more stress than the bulk, confirming a strong bonding between the nanoparticles. Moreover, this technique allows the measurement of the surface diffusion coefficient from experimental observations, which we compute for the Au nanoparticles. This methodology can be used for any metal, oxide, semiconductor or combination of them.

  1. Single particle nonlocality, geometric phases and time-dependent boundary conditions

    Science.gov (United States)

    Matzkin, A.

    2018-03-01

    We investigate the issue of single particle nonlocality in a quantum system subjected to time-dependent boundary conditions. We discuss earlier claims according to which the quantum state of a particle remaining localized at the center of an infinite well with moving walls would be specifically modified by the change in boundary conditions due to the wall’s motion. We first prove that the evolution of an initially localized Gaussian state is not affected nonlocally by a linearly moving wall: as long as the quantum state has negligible amplitude near the wall, the boundary motion has no effect. This result is further extended to related confined time-dependent oscillators in which the boundary’s motion is known to give rise to geometric phases: for a Gaussian state remaining localized far from the boundaries, the effect of the geometric phases is washed out and the particle dynamics shows no traces of a nonlocal influence that would be induced by the moving boundaries.

  2. Conceptual Design of a Single-Aisle Turboelectric Commercial Transport With Fuselage Boundary Layer Ingestion

    Science.gov (United States)

    Welstead, Jason R.; Felder, James L.

    2016-01-01

    A single-aisle commercial transport concept with a turboelectric propulsion system architecture was developed assuming entry into service in 2035 and compared to a similar technology conventional configuration. The turboelectric architecture consisted of two underwing turbofans with generators extracting power from the fan shaft and sending it to a rear fuselage, axisymmetric, boundary layer ingesting fan. Results indicate that the turbo- electric concept has an economic mission fuel burn reduction of 7%, and a design mission fuel burn reduction of 12% compared to the conventional configuration. An exploration of the design space was performed to better understand how the turboelectric architecture changes the design space, and system sensitivities were run to determine the sensitivity of thrust specific fuel consumption at top of climb and propulsion system weight to the motor power, fan pressure ratio, and electrical transmission efficiency of the aft boundary layer ingesting fan.

  3. Switching features of GMO single crystals by contrary motion of pair planar domain boundaries

    International Nuclear Information System (INIS)

    Alekseev, A.N.

    2003-01-01

    Gadolinium molybdate single crystal specimens in the form of square plates 1.2 mm thick, which provide similar conditions of nucleation of domains with differently oriented planar domain boundaries (PDB), are used to study processes of total change-over of orientation states by compressing mechanical action applied alternately to one of two pairs of opposite end faces of the specimen. It is revealed that successive acts of such change-over are always carried out by PDB pairs of alternating mutually orthogonal orientation. A closing stage for every successive change-over is realized through a collapse of either wedge-like or lenticular domain [ru

  4. Casimir effect due to a single boundary as a manifestation of the Weyl problem

    Science.gov (United States)

    Kolomeisky, Eugene B.; Straley, Joseph P.; Langsjoen, Luke S.; Zaidi, Hussain

    2010-09-01

    The Casimir self-energy of a boundary is ultraviolet-divergent. In many cases, the divergences can be eliminated by methods such as zeta-function regularization or through physical arguments (ultraviolet transparency of the boundary would provide a cutoff). Using the example of a massless scalar field theory with a single Dirichlet boundary, we explore the relationship between such approaches, with the goal of better understanding of the origin of the divergences. We are guided by the insight due to Dowker and Kennedy (1978 J. Phys. A: Math. Gen. 11 895) and Deutsch and Candelas (1979 Phys. Rev. D 20 3063) that the divergences represent measurable effects that can be interpreted with the aid of the theory of the asymptotic distribution of eigenvalues of the Laplacian discussed by Weyl. In many cases, the Casimir self-energy is the sum of cutoff-dependent (Weyl) terms having a geometrical origin, and an 'intrinsic' term that is independent of the cutoff. The Weyl terms make a measurable contribution to the physical situation even when regularization methods succeed in isolating the intrinsic part. Regularization methods fail when the Weyl terms and intrinsic parts of the Casimir effect cannot be clearly separated. Specifically, we demonstrate that the Casimir self-energy of a smooth boundary in two dimensions is a sum of two Weyl terms (exhibiting quadratic and logarithmic cutoff dependence), a geometrical term that is independent of cutoff and a non-geometrical intrinsic term. As by-products, we resolve the puzzle of the divergent Casimir force on a ring and correct the sign of the coefficient of linear tension of the Dirichlet line predicted in earlier treatments.

  5. A visualization method for probing grain boundaries of single layer graphene via molecular beam epitaxy

    Science.gov (United States)

    Zhan, Linjie; Wan, Wen; Zhu, Zhenwei; Zhao, Zhijuan; Zhang, Zhenhan; Shih, Tien-Mo; Cai, Weiwei

    2017-07-01

    Graphene, a member of layered two-dimensional (2D) materials, possesses high carrier mobility, mechanical flexibility, and optical transparency, as well as enjoying a wide range of promising applications in electronics. Adopting the chemical vaporization deposition method, the majority of investigators have ubiquitously grown single layer graphene (SLG), which inevitably involves polycrystalline properties. Here we demonstrate a simple method for the direct visualization of arbitrarily large-size SLG domains by synthesizing one-hundred-nm-scale MoS2 single crystals via a high-vacuum molecular beam epitaxy process. The present study based on epitaxial growth provides a guide for probing the grain boundaries of various 2D materials and implements higher potentials for the next-generation electronic devices.

  6. Retrieving 4-dimensional atmospheric boundary layer structure from surface observations and profiles over a single station

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Zhaoxia [Univ. of Utah, Salt Lake City, UT (United States)

    2015-10-06

    Most routine measurements from climate study facilities, such as the Department of Energy’s ARM SGP site, come from individual sites over a long period of time. While single-station data are very useful for many studies, it is challenging to obtain 3-dimensional spatial structures of atmospheric boundary layers that include prominent signatures of deep convection from these data. The principal objective of this project is to create realistic estimates of high-resolution (~ 1km × 1km horizontal grids) atmospheric boundary layer structure and the characteristics of precipitating convection. These characteristics include updraft and downdraft cumulus mass fluxes and cold pool properties over a region the size of a GCM grid column from analyses that assimilate surface mesonet observations of wind, temperature, and water vapor mixing ratio and available profiling data from single or multiple surface stations. The ultimate goal of the project is to enhance our understanding of the properties of mesoscale convective systems and also to improve their representation in analysis and numerical simulations. During the proposed period (09/15/2011–09/14/2014) and the no-cost extension period (09/15/2014–09/14/2015), significant accomplishments have been achieved relating to the stated goals. Efforts have been extended to various research and applications. Results have been published in professional journals and presented in related science team meetings and conferences. These are summarized in the report.

  7. Heterochromatin and the molecular mechanisms of 'parent-of-origin ...

    Indian Academy of Sciences (India)

    2016-11-30

    Nov 30, 2016 ... Department of Natural Sciences and Psychology, Liverpool John Moores University,. Life Sciences Building, Byrom Street, Liverpool L3 3AF, UK. (Email, prim.singh@charite.de; P.Singh@ljmu.ac.uk). Twenty five years ago it was proposed that conserved components of constitutive heterochromatin ...

  8. Distribution of constitutive heterochromatin in Triatoma melanocephala (Hemiptera, Triatominae).

    Science.gov (United States)

    Alevi, K C C; Rosa, J A; Azeredo-Oliveira, M T V

    2014-09-29

    In principle, Triatoma melanocephala was included in the Brasiliensis subcomplex on the basis of morphological parameters and geographical layout, since there were no other relevant data available in the literature. On the basis of karyotype, it has been proposed to exclude T. melanocephala, as well as of T. vitticeps and T. tibiamaculata, from the subcomplex, which shows fragmentation of the X sex chromosomes, thereby approaching the species of North America. Therefore, the present study aimed to determine the pattern of constitutive heterochromatin of T. melanocephala to provide new data on the cytotaxonomy of this vector of Chagas disease and especially to try to relate this species to some group, complex or subcomplex of triatomine species, aiding in their classification. This species showed no constitutive heterochromatin in the autosomes or X sex chromosome, but only the Y sex chromosome. The number of chromosomes and heterochromatin pattern of T. melanocephala proved to be identical to that described for Panstrongylus lutzi. Thus, the present study demonstrated a tentative relationship between T. melanocephala and P. lutzi. However, we emphasize that other comparative studies should be conducted between these species, such as experimental crosses and molecular, enzymatic, morphological, and morphometric analyses to determine whether these species are actually evolutionarily related or if the number of chromosomes and the heterochromatin pattern emerged as homoplasies in T. melanocephala and P. lutzi.

  9. Single-Column Model Simulations of Subtropical Marine Boundary-Layer Cloud Transitions Under Weakening Inversions

    Science.gov (United States)

    Neggers, R. A. J.; Ackerman, A. S.; Angevine, W. M.; Bazile, E.; Beau, I.; Blossey, P. N.; Boutle, I. A.; de Bruijn, C.; Cheng, A.; van der Dussen, J.; Fletcher, J.; Dal Gesso, S.; Jam, A.; Kawai, H.; Cheedela, S. K.; Larson, V. E.; Lefebvre, M.-P.; Lock, A. P.; Meyer, N. R.; de Roode, S. R.; de Rooy, W.; Sandu, I.; Xiao, H.; Xu, K.-M.

    2017-10-01

    Results are presented of the GASS/EUCLIPSE single-column model intercomparison study on the subtropical marine low-level cloud transition. A central goal is to establish the performance of state-of-the-art boundary-layer schemes for weather and climate models for this cloud regime, using large-eddy simulations of the same scenes as a reference. A novelty is that the comparison covers four different cases instead of one, in order to broaden the covered parameter space. Three cases are situated in the North-Eastern Pacific, while one reflects conditions in the North-Eastern Atlantic. A set of variables is considered that reflects key aspects of the transition process, making use of simple metrics to establish the model performance. Using this method, some longstanding problems in low-level cloud representation are identified. Considerable spread exists among models concerning the cloud amount, its vertical structure, and the associated impact on radiative transfer. The sign and amplitude of these biases differ somewhat per case, depending on how far the transition has progressed. After cloud breakup the ensemble median exhibits the well-known "too few too bright" problem. The boundary-layer deepening rate and its state of decoupling are both underestimated, while the representation of the thin capping cloud layer appears complicated by a lack of vertical resolution. Encouragingly, some models are successful in representing the full set of variables, in particular, the vertical structure and diurnal cycle of the cloud layer in transition. An intriguing result is that the median of the model ensemble performs best, inspiring a new approach in subgrid parameterization.

  10. [The role of DNA methylation and histone modifications in structural maintainance of heterochromatin domains (chromocenters)].

    Science.gov (United States)

    Golyshev, S A; Vikhreva, P N; Sheval', E V; Kir'ianov, G I; Poliakov, V Iu

    2008-01-01

    The effects of DNA methylation inhibitor 5-azacytidine (5-aza-C) and histone acetylation inhibitor trichostatine A (TSA) on the structure of pericentric heterochromatin in cultured mouse cells (L929) has been studied. After 48 h of 5-aza-C treatment, about 85% of the cells demonstrate transformation of chromocenters from ovoid to elongated structures. Hypotonic treatment of these cells reveals tandemly arranged DAPI-positive globules, well distinguishable by light microscopy. The same globular units can be revealed in hypotonic-treated control cells. 48 h of TSA treatment causes dramatic decrease in HP 1alpha content in the cells. Chromocenters in 25% of treated cells became highly decondenced and can not be reliably detected by light and electron microscopy. 85% of cells demonstrate globular chromocenters with low HP 1alpha content. Hypotonic treatment causes transformation of compact chromocenters into ring-like structures, which can be either single or clustered. Rings are formed by uniform fiber, in which no globular subunits are detected. The data obtained are discussed concerning several mechanisms of heterochromatin structure maintenance and the roles of epigenetic marks in them.

  11. Nuclear DNA content, base composition, heterochromatin and rDNA in Picea omorika and Picea abies.

    Science.gov (United States)

    Siljak-Yakovlev, S.; Cerbah, M.; Coulaud, J.; Stoian, V.; Brown, S. C.; Zoldos, V.; Jelenic, S.; Papes, D.

    2002-02-01

    Two closely related spruces, Picea abies and Picea omorika, a Balkan paleoendemic species, often share habitats, yet never hybridize in nature. The present study adresses their characteristics such as nuclear DNA content, base composition, heterochromatin and rDNA pattern. The genome size of P. abies was 10% larger than that of P. omorika when assessed by flow cytometry, respectively 2C=37.2 pg and 33.8 pg; although when estimated as total chromosome length it was virtually the same. The heterochromatin Chromomycin-A (CMA)/ DAPI fluorochrome banding patterns of both P. abies and P. omorikaare given here for the first time. Simultaneous FISH (fluorescent in situ hybridization) using 18S-26S and 5S rDNA probes revealed 16 18S rDNA sites in P. omorika, 12 18S rDNA sites in P. abies, and a single 5S rDNA locus in both species. The genomes have about 41% GC. The number and position of CMA/DAPI bands and rDNA loci provide good chromosome markers to clarify the karyotypes of the two species.

  12. Heterochromatin heterogeneity in Hypostomus prope unae (Steindachner, 1878 (Siluriformes, Loricariidae from Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Jamille Bitencourt

    2011-11-01

    Full Text Available Cytogenetic analyses using C-banding and chromosomal digestion by several restriction enzymes were carried out in four populations (named A, B, C and D of Hypostomus prope unae (Loricariidae, Hypostominae from Contas river basin, northeastern Brazil. These populations share 2n=76 and single NORs on the second metacentric pair but exclusive karyotype forms for each locality. Populations A and B presented conspicuous terminal and interstitial heterochromatic blocks on most of acrocentric chromosomes and equivalent to NORs with differences in both position and bearing pair. Population D showed evident marks at interstitial regions and interspersed with nucleolar region while population C presented interstitial and terminal heterochromatin segments, non-coincident with NORs. The banding pattern after digestion with the endonucleases Alu I, Bam HI, Hae III and Dde I revealed a remarkable heterogeneity within heterochromatin, allowing the identification of distinctive clusters of repeated DNA in the studied populations, besides specific patterns along euchromatic regions. The analysis using restriction enzymes has proved to be highly informative, characterizing population differences and peculiarities in the genome organization of H. prope unae.

  13. Empirical reconstruction and long-duration tracking of the magnetospheric boundary in single- and multi-spacecraft contexts

    Directory of Open Access Journals (Sweden)

    J. De Keyser

    2005-06-01

    Full Text Available The magnetospheric boundary is always moving, making it difficult to establish its structure. This paper presents a novel method for tracking the motion of the boundary, based on in-situ observations of the plasma velocity and of one or more additional observables. This method allows the moving boundary to be followed for extended periods of time (up to several hours and aptly deals with limitations on the time resolution of the data, with measurement errors, and with occasional data gaps; it can exploit data from any number of spacecraft and any type of instrument. At the same time the method is an empirical reconstruction technique that determines the one-dimensional spatial structure of the boundary. The method is illustrated with single- and multi-spacecraft applications using data from Ampte/Irm and Cluster.

  14. Flux flow and pinning by twin boundaries in single crystal YBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Kwok, W.K.; Fleshler, S.; Welp, U.; Vinokur, V.M.; Downey, J.; Crabtree, G.W.

    1993-01-01

    We present AC magnetoresistance measurements in fully oxygenated and oxygen deficient single crystals of YBa 2 Cu 3 O 7-δ . From the resistive broadening in magnetic field for H parallel ab parallel I and H parallel ab perpendicular to I, we demonstrate the existence of Lorentz force induced flux flow dissipation near T c . Using a novel crossed magnetic field technique where high angular resolution of Δθ 2 Cu 3 O 7-δ single crystals. The twin boundary pinning onset is characterized by a critical angle model and we extract a phase diagram for the onset of twin boundary pinning. We report on a strong magnetic field dependence of the critical angle for twin boundary pinning for H parallel c which is absent for H parallel ab. In addition, we find the critical angle θ * for H parallel c is greater than that observed for H parallel ab for nearly stoichiometric samples. (orig.)

  15. Temporal and spatial evolution characteristics of disturbance wave in a hypersonic boundary layer due to single-frequency entropy disturbance.

    Science.gov (United States)

    Wang, Zhenqing; Tang, Xiaojun; Lv, Hongqing; Shi, Jianqiang

    2014-01-01

    By using a high-order accurate finite difference scheme, direct numerical simulation of hypersonic flow over an 8° half-wedge-angle blunt wedge under freestream single-frequency entropy disturbance is conducted; the generation and the temporal and spatial nonlinear evolution of boundary layer disturbance waves are investigated. Results show that, under the freestream single-frequency entropy disturbance, the entropy state of boundary layer is changed sharply and the disturbance waves within a certain frequency range are induced in the boundary layer. Furthermore, the amplitudes of disturbance waves in the period phase are larger than that in the response phase and ablation phase and the frequency range in the boundary layer in the period phase is narrower than that in these two phases. In addition, the mode competition, dominant mode transformation, and disturbance energy transfer exist among different modes both in temporal and in spatial evolution. The mode competition changes the characteristics of nonlinear evolution of the unstable waves in the boundary layer. The development of the most unstable mode along streamwise relies more on the motivation of disturbance waves in the upstream than that of other modes on this motivation.

  16. Detritus in K/T boundary clays of western North America - Evidence against a single oceanic impact

    Science.gov (United States)

    Sharpton, V. L.; Schuraytz, B. C.; Burke, K.; Murali, A. V.; Ryder, G.

    1990-01-01

    Understanding the crustal signature of impact ejecta contained in the Cretaceous/Tertiary (K/T) boundary layer is crucial to constraining the possible site(s) of the postulated K/T impact event. The relatively unaltered clastic constituents of the boundary layer at widely separated outcrops within the western interior of North America are not compatible with a single oceanic impact but require instead an impact site on a continent or continental margin. On the other hand, chemical compositions of highly altered K/T boundary layer components in some marine sections have suggested to others an impact into oceanic crust. We suspect that post-depositional alteration within the marine setting accounts for this apparent oceanic affinity. If, however, this is not the case, multiple simultaneous impacts, striking continent as well as ocean floor, would seem to be required.

  17. Enhancement of single mode operation in coaxial optical waveguide using DB boundary conditions

    Science.gov (United States)

    Lohia, Pooja; Prajapati, Y.; Saini, J. P.; Rai, B. S.

    2014-11-01

    In this study, a competent numerical strategy to compute the dispersion of optical waveguides is presented and propagation of electromagnetic waves in a coaxial optical waveguide with DB boundary conditions is instigated. For this intend, cylindrical coordinates are here being used to derive the DB boundary conditions and to obtain field components for the modes. The propagation constant for the waveguide to be studied is determined by solving the Bessel and the modified Bessel functions. The cutoff frequencies for various lower order modes have been calculated and their dispersion characteristics are plotted correspondingly. The behavior of the coaxial optical waveguide under DB boundary conditions is shown to be significantly different from that of coaxial optical waveguide and conventional optical waveguide under traditional or tangential boundary conditions. Finally, the effect of waveguide dimensions on the mode cutoff frequencies and fabrication issues are also addressed.

  18. Single Grain Boundary Modeling and Design of Microcrystalline Si Solar Cells

    OpenAIRE

    Lin, Chu-Hsuan; Hsu, Wen-Tzu; Tai, Cheng-Hung

    2013-01-01

    For photovoltaic applications, microcrystalline silicon has a lot of advantages, such as the ability to absorb the near-infrared part of the solar spectrum. However, there are many dangling bonds at the grain boundary in microcrystalline Si. These dangling bonds would lead to the recombination of photo-generated carriers and decrease the conversion efficiency. Therefore, we included the grain boundary in the numerical study in order to simulate a microcrystalline Si solar cell accurately, des...

  19. Study of magnetic field distribution in anisotropic single twin-boundary magnetic shape memory (MSM) element in actuators

    Science.gov (United States)

    Gabdullin, N.; Khan, S. H.

    2017-10-01

    Magnetic shape memory effect exhibited by certain alloys at room temperature is known for almost 20 years. The most studied MSM alloys are Ni-Mn-Ga alloys which exhibit up to 12% magnetic field-induced strain (change in shape) depending on microstructure. A multibillion cycle operation without malfunction along with their “smart” properties make them very promising for application in electromagnetic (EM) actuators and sensors. However, considerable twinning stress of MSM crystals resulting in magneto-mechanical hysteresis decreases the efficiency and output force of MSM actuators. Whereas twinning stress of conventional MSM crystals has been significantly decreased over the years, novel crystals with Type II twin boundaries (TBs) possess even lower twinning stress. Unfortunately, the microstructure of MSM crystals with very low twinning stress tends to be unstable leading to their rapid crack growth. Whilst this phenomenon has been studied experimentally, the magnetic field distribution in anisotropic single twin-boundary MSM elements has not been considered yet. This paper analyses the magnetic field distribution in two-variant single twin-boundary MSM elements and discusses its effects on magnetic field-induced stress acting on the twin boundary.

  20. Silencing markers are retained on pericentric heterochromatin during murine primordial germ cell development

    NARCIS (Netherlands)

    A.M. Magaraki (Aristea); G.W. van der Heijden (Godfried); E. Sleddens-Linkels (Esther); Magarakis, L. (Leonidas); W.A. van Cappellen (Gert); A.H.F.M. Peters (Antoine H. F. M.); J.H. Gribnau (Joost); W.M. Baarends (Willy); M. Eijpe (Maureen)

    2017-01-01

    textabstractBackground: In the nuclei of most mammalian cells, pericentric heterochromatin is characterized by DNA methylation, histone modifications such as H3K9me3 and H4K20me3, and specific binding proteins like heterochromatin-binding protein 1 isoforms (HP1 isoforms). Maintenance of this

  1. Negative Regulators of an RNAi-Heterochromatin Positive Feedback Loop Safeguard Somatic Genome Integrity in Tetrahymena.

    Science.gov (United States)

    Suhren, Jan H; Noto, Tomoko; Kataoka, Kensuke; Gao, Shan; Liu, Yifan; Mochizuki, Kazufumi

    2017-03-07

    RNAi-mediated positive feedback loops are pivotal for the maintenance of heterochromatin, but how they are downregulated at heterochromatin-euchromatin borders is not well understood. In the ciliated protozoan Tetrahymena, heterochromatin is formed exclusively on the sequences that are removed from the somatic genome by programmed DNA elimination, and an RNAi-mediated feedback loop is important for assembling heterochromatin on the eliminated sequences. In this study, we show that the heterochromatin protein 1 (HP1)-like protein Coi6p, its interaction partners Coi7p and Lia5p, and the histone demethylase Jmj1p are crucial for confining the production of small RNAs and the formation of heterochromatin to the eliminated sequences. The loss of Coi6p, Coi7p, or Jmj1p causes ectopic DNA elimination. The results provide direct evidence for the existence of a dedicated mechanism that counteracts a positive feedback loop between RNAi and heterochromatin at heterochromatin-euchromatin borders to maintain the integrity of the somatic genome. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  2. The proper splicing of RNAi factors is critical for pericentric heterochromatin assembly in fission yeast.

    Directory of Open Access Journals (Sweden)

    Scott P Kallgren

    Full Text Available Heterochromatin preferentially assembles at repetitive DNA elements, playing roles in transcriptional silencing, recombination suppression, and chromosome segregation. The RNAi machinery is required for heterochromatin assembly in a diverse range of organisms. In fission yeast, RNA splicing factors are also required for pericentric heterochromatin assembly, and a prevailing model is that splicing factors provide a platform for siRNA generation independently of their splicing activity. Here, by screening the fission yeast deletion library, we discovered four novel splicing factors that are required for pericentric heterochromatin assembly. Sequencing total cellular RNAs from the strongest of these mutants, cwf14Δ, showed intron retention in mRNAs of several RNAi factors. Moreover, introducing cDNA versions of RNAi factors significantly restored pericentric heterochromatin in splicing mutants. We also found that mutations of splicing factors resulted in defective telomeric heterochromatin assembly and mis-splicing the mRNA of shelterin component Tpz1, and that replacement of tpz1+ with its cDNA partially rescued heterochromatin defects at telomeres in splicing mutants. Thus, proper splicing of RNAi and shelterin factors contributes to heterochromatin assembly at pericentric regions and telomeres.

  3. The Human Protein PRR14 Tethers Heterochromatin to the Nuclear Lamina during Interphase and Mitotic Exit

    Directory of Open Access Journals (Sweden)

    Andrey Poleshko

    2013-10-01

    Full Text Available The nuclear lamina is a protein meshwork that lies under the inner nuclear membrane of metazoan cells. One function of the nuclear lamina is to organize heterochromatin at the inner nuclear periphery. However, very little is known about how heterochromatin attaches to the nuclear lamina and how such attachments are restored at mitotic exit. Here, we show that a previously unstudied human protein, PRR14, functions to tether heterochromatin to the nuclear periphery during interphase, through associations with heterochromatin protein 1 (HP1 and the nuclear lamina. During early mitosis, PRR14 is released from the nuclear lamina and chromatin and remains soluble. Strikingly, at the onset of anaphase, PRR14 is incorporated rapidly into chromatin through HP1 binding. Finally, in telophase, PRR14 relocalizes to the reforming nuclear lamina. This stepwise reassembly of PRR14 suggests a function in the selection of HP1-bound heterochromatin for reattachment to the nuclear lamina as cells exit mitosis.

  4. Mechanism for full-length RNA processing of Arabidopsis genes containing intragenic heterochromatin.

    Science.gov (United States)

    Saze, Hidetoshi; Kitayama, Junko; Takashima, Kazuya; Miura, Saori; Harukawa, Yoshiko; Ito, Tasuku; Kakutani, Tetsuji

    2013-01-01

    Genomes of higher eukaryotes contain many transposable elements, which often localize within the transcribed regions of active genes. Although intragenic transposable elements can be silenced to form heterochromatin, the impact of intragenic heterochromatin on transcription and RNA processing remains largely unexplored. Here we show using a flowering plant, Arabidopsis, that full-length transcript formation over intragenic heterochromatin depends on a protein named IBM2 (Increase in Bonsai Methylation 2), which has a Bromo-Adjacent Homology domain and an RNA recognition motif. Mutation of ibm2 triggers premature termination of transcripts with 3' RNA processing around intragenic heterochromatin at loci including the H3K9 demethylase gene IBM1. The need for IBM2 is circumvented in variant alleles that lack the heterochromatic domain. Our results reveal a mechanism that masks deleterious effects of intragenic heterochromatin, providing evolutionary sources for genetic and epigenetic variations.

  5. An Interaction between RRP6 and SU(VAR)3-9 Targets RRP6 to Heterochromatin and Contributes to Heterochromatin Maintenance in Drosophila melanogaster

    Science.gov (United States)

    Eberle, Andrea B.; Jordán-Pla, Antonio; Gañez-Zapater, Antoni; Hessle, Viktoria; Silberberg, Gilad; von Euler, Anne; Silverstein, Rebecca A.; Visa, Neus

    2015-01-01

    RNA surveillance factors are involved in heterochromatin regulation in yeast and plants, but less is known about the possible roles of ribonucleases in the heterochromatin of animal cells. Here we show that RRP6, one of the catalytic subunits of the exosome, is necessary for silencing heterochromatic repeats in the genome of Drosophila melanogaster. We show that a fraction of RRP6 is associated with heterochromatin, and the analysis of the RRP6 interaction network revealed physical links between RRP6 and the heterochromatin factors HP1a, SU(VAR)3-9 and RPD3. Moreover, genome-wide studies of RRP6 occupancy in cells depleted of SU(VAR)3-9 demonstrated that SU(VAR)3-9 contributes to the tethering of RRP6 to a subset of heterochromatic loci. Depletion of the exosome ribonucleases RRP6 and DIS3 stabilizes heterochromatic transcripts derived from transposons and repetitive sequences, and renders the heterochromatin less compact, as shown by micrococcal nuclease and proximity-ligation assays. Such depletion also increases the amount of HP1a bound to heterochromatic transcripts. Taken together, our results suggest that SU(VAR)3-9 targets RRP6 to a subset of heterochromatic loci where RRP6 degrades chromatin-associated non-coding RNAs in a process that is necessary to maintain the packaging of the heterochromatin. PMID:26389589

  6. Effects of physical boundary conditions on the transverse vibration of single-layer graphene sheets

    Science.gov (United States)

    Sadeghzadeh, S.; Khatibi, M. M.

    2016-09-01

    The effects of various approaches for a comprehensive application of boundary conditions on the molecular dynamics of graphene nanosheets were studied in this paper. Fixing more than two rows of carbon atoms was tested for satisfaction of clamped boundary condition in dynamics problems, and it was demonstrated that a completely different view should be taken for clamped boundary conditions. To do this, through the frequency domain decomposition approach, operational modal analysis has been developed to carry out the Laboratory of Nanometric Operational Modal Analysis on a molecular dynamics platform. The theory of the mentioned approach was introduced, and some comparisons were made with experimental works. The modeling results have shown that for graphene sheets with simply supported edges, fixing two or more rows leads to the same response as fixing one row. For clamped edges, the use of a flexible base as a substrate satisfies the boundary condition with the best possible. At the end, as an example, it has been demonstrated that the second and third natural vibration frequencies increase with the increase in aspect ratio, while the first frequency remains unchanged.

  7. Temperature dependence of single twin boundary motion in Ni–Mn–Ga martensite

    Czech Academy of Sciences Publication Activity Database

    Straka, L.; Hänninen, H.; Heczko, Oleg

    2011-01-01

    Roč. 98, č. 14 (2011), 141902/1-141902/3 ISSN 0003-6951 Grant - others:AVČR(CZ) M100100913 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic shape memory effect * modulated martensite * Ni-Mn-Ga * mobility of twin boundary Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.844, year: 2011

  8. Single Grain Boundary Modeling and Design of Microcrystalline Si Solar Cells

    Directory of Open Access Journals (Sweden)

    Chu-Hsuan Lin

    2013-01-01

    Full Text Available For photovoltaic applications, microcrystalline silicon has a lot of advantages, such as the ability to absorb the near-infrared part of the solar spectrum. However, there are many dangling bonds at the grain boundary in microcrystalline Si. These dangling bonds would lead to the recombination of photo-generated carriers and decrease the conversion efficiency. Therefore, we included the grain boundary in the numerical study in order to simulate a microcrystalline Si solar cell accurately, designing new three-terminal microcrystalline Si solar cells. The 3-μm-thick three-terminal cell achieved a conversion efficiency of 10.8%, while the efficiency of a typical two-terminal cell is 9.7%. The three-terminal structure increased the JSC but decreased the VOC, and such phenomena are discussed. High-efficiency and low-cost Si-based thin film solar cells can now be designed based on the information provided in this paper.

  9. Single Grain Boundary Modeling and Design of Microcrystalline Si Solar Cells.

    Science.gov (United States)

    Lin, Chu-Hsuan; Hsu, Wen-Tzu; Tai, Cheng-Hung

    2013-01-21

    For photovoltaic applications, microcrystalline silicon has a lot of advantages, such as the ability to absorb the near-infrared part of the solar spectrum. However, there are many dangling bonds at the grain boundary in microcrystalline Si. These dangling bonds would lead to the recombination of photo-generated carriers and decrease the conversion efficiency. Therefore, we included the grain boundary in the numerical study in order to simulate a microcrystalline Si solar cell accurately, designing new three-terminal microcrystalline Si solar cells. The 3-μm-thick three-terminal cell achieved a conversion efficiency of 10.8%, while the efficiency of a typical two-terminal cell is 9.7%. The three-terminal structure increased the J SC but decreased the V OC , and such phenomena are discussed. High-efficiency and low-cost Si-based thin film solar cells can now be designed based on the information provided in this paper.

  10. Critical firing and misfiring boundary in a spark ignition methanol engine during cold start based on single cycle fuel injection

    International Nuclear Information System (INIS)

    Li, Zhaohui; Gong, Changming; Qu, Xiang; Liu, Fenghua; Sun, Jingzhen; Wang, Kang; Li, Yufeng

    2015-01-01

    The influence of the mass of methanol injected per cycle, ambient temperature, injection and ignition timing, preheating methods, and supplying additional liquefied petroleum gas (LPG) injection into the intake manifold on the critical firing and misfiring boundary of an electronically injection controlled spark ignition (SI) methanol engine during cold start were investigated experimentally based on a single cycle fuel injection with cycle-by-cycle control strategy. The critical firing and misfiring boundary was restricted by all parameters. For ambient temperatures below 16 °C, methanol engines must use auxiliary start-aids during cold start. Optimal control of the methanol injection and ignition timing can realize ideal next cycle firing combustion after injection. Resistance wire and glow plug preheating can provide critical firing down to ambient temperatures of 5 °C and 0 °C, respectively. Using an additional LPG injection into the intake manifold can provide critical firing down to an ambient temperature of −13 °C during cold start. As the ambient temperature decreases, the optimal angle difference between methanol injection timing and LPG injection timing for critical firing of a methanol engine increases rapidly during cold start. - Highlights: • A single cycle fuel injection and cycle-by-cycle control strategy are used to study. • In-cylinder pressure and instantaneous speed were used to determine firing boundary. • For the ambient temperatures below 16 °C, an auxiliary start-aids must be used. • A preheating and additional LPG were used to expand critical firing boundary. • Additional LPG can result in critical firing down to ambient temperature of −13 °C

  11. A Comparison between Boundary and Continuous Conduction Modes in Single Phase PFC Using 600V Range Devices

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

    2015-01-01

    This paper presents an analysis and comparison of boundary conduction mode (BCM) and continuous conduction mode (CCM) in single phase power factor correction (PFC) applications. The comparison is based on double pulse tester (DPT) characterization results of state-of-the-art superjunction devices...... in the 600V range. The measured switching energy is used to evaluate the devices performance in a conventional PFC. This data is used together with a mathematical model for prediction of the conducted electromagnetic interference (EMI). This allows comparing the different devices in BCM and CCM operation...... modes and evaluating the performance as a function of the PFC power density and efficiency....

  12. Exploring the boundary-layer cloud-climate feedback through Single-Column Model in Radiative-Advective Equilibrium

    Science.gov (United States)

    Dal Gesso, Sara; Neggers, Roel

    2017-04-01

    Boundary-layer clouds remain the major contributor to the inter-model spread in future climate predictions. Although light has been shed on the low-level cloud feedback, much remains to be understood about the physical mechanisms at the basis of the response of these clouds to climate warming. In the present study, EC-EARTH Single Column Model (SCM) is used to explore the boundary-layer cloud-climate feedback by imposing a Radiative-Advective Equilibrium, namely a balance between the radiative cooling and the advection of warm air. 30-year simulations are performed with the SCM forced by high-frequency cfSites outputs of the CMIP5 simulations of the host General Circulation Model (GCM) for both the AMIP and AMIP4K experiments. As this study exclusively focuses on marine low-level cloud regimes, the simulations are performed at the Barbados Cloud Observatory in the so-called "dry period", when the large-scale forcing are representative of subtropical marine trade-wind conditions. A first step is to assess how representative long-term SCM simulations are of their host GCM. Subsequently, the SCM is forced by different GCMs within the same framework. In this way, the contribution of the physical parameterization to the boundary-layer cloud feedback is isolated from the dynamics, and systematically evaluated. Finally, a procedure to integrate Large-Eddy Simulations and observations into this framework is discussed.

  13. Imaging the Structure of Grains, Grain Boundaries, and Stacking Sequences in Single and Multi-Layer Graphene

    Science.gov (United States)

    Muller, David

    2012-02-01

    Graphene can be produced by chemical vapor deposition (CVD) on copper substrates on up to meter scales [1, 2], making their polycrystallinity [3,4] almost unavoidable. By combining aberration-corrected scanning transmission electron microscopy and dark-field transmission electron microscopy, we image graphene grains and grain boundaries across six orders of magnitude. Atomic-resolution images of graphene grain boundaries reveal that different grains can stitch together via pentagon-heptagon pairs. We use diffraction-filtered electron imaging to map the shape and orientation of several hundred grains and boundaries over fields of view of a hundred microns. Single, double and multilayer graphene can be differentiated, and the stacking sequence and relative abundance of sequences can be directly imaged. These images reveal an intricate patchwork of grains with structural details depending strongly on growth conditions. The imaging techniques enabled studies of the structure, properties, and control of graphene grains and grain boundaries [5]. [4pt] [1] X. Li et al., Science 324, 1312 (2009).[0pt] [2] S. Bae et al., Nature Nanotechnol. 5, 574 (2010).[0pt] [3] J. M. Wofford, et al., Nano Lett., (2010).[0pt] [4] P. Y. Huang, et al., Nature 469, 389--392 (2011); arXiv:1009.4714, (2010)[0pt] [5] In collaboration with Pinshane Y. Huang, C. S. Ruiz-Vargas, A. M. van der Zande, A. W. Tsen, L. Brown, R. Hovden, F. Ghahari, W. S. Whitney, M.P. Levendorf, J. W. Kevek, S. Garg, J. S. Alden, C. J. Hustedt, Y. Zhu, N. Petrone, J. Hone, J. Park, P. L. McEuen

  14. Anisotropy of vortex creep in YBa2Cu3O7-x single crystals with unidirectional twin boundaries

    International Nuclear Information System (INIS)

    Bondarenko, A.V.; Revyakina, M.G.; Prodan, A.A.; Obolenskij, M.A.; Vovk, R.V.; Arouri, T.R.

    2001-01-01

    The creep of Abrikosov vortices in a YBa 2 Cu 3 O 7-x single crystal containing unidirectional twin boundaries (TB's) was investigated in a special experimental geometry: J parallel ab, J parallel TB, H perpendicular J, and α ident to angle H, ab was a variable parameter. It is shown that the TB's affect the configuration structure of vortex lines for disorientation angles θ between magnetic field vector and TB's planes up to 70: at angles θ current J cE , observed in low magnetic fields for H parallel ab, is replaced by a minimum in high magnetic fields. This behavior is explained by the change-over from the single vortex creep to a collective one with increasing magnetic field

  15. Stability boundary analysis in single-phase grid-connected inverters with PLL by LTP theory

    OpenAIRE

    Salis, Valerio; Costabeber, Alessando; Cox, Stephen M.; Zanchetta, Pericle; Formentini, Andrea

    2017-01-01

    Stability analysis of power converters in AC net¬works is complex due to the non-linear nature of the conversion systems. Whereas interactions of converters in DC networks can be studied by linearising about the operating point, the extension of the same approach to AC systems poses serious challenges, especially for single-phase or unbalanced three-phase systems. A general method for stability analysis of power converters suitable for single-phase or unbalanced AC networks is presented in th...

  16. Formation of grain boundaries in magnesium single crystal during equal channel angular pressing

    Czech Academy of Sciences Publication Activity Database

    Šedá, P.; Jäger, Aleš; Lejček, Pavel; Triguero, P.R.

    2014-01-01

    Roč. 94, č. 10 (2014), s. 1095-1111 ISSN 1478-6435 R&D Projects: GA ČR GBP108/12/G043; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : magnesium * ECAP * single crystal * EBSD * recrystallization Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.825, year: 2014

  17. Single-column model and large eddy simulation of the evening transition in the planetary boundary layer

    Science.gov (United States)

    Cuchiara, Gustavo; Rappenglück, Bernhard

    2016-04-01

    The transition from the convective boundary layer during the daytime to the stable stratified boundary layer during nighttime after sunset plays an important role in the transport and dispersion of atmospheric pollutants. However, our knowledge regarding this transition and its feedback on the structure of the subsequent nocturnal boundary layer is still restricted. This also prevents forecast models from accurate prediction of the onset and development of the nighttime boundary layer, which determines the redistribution of pollutants within the nocturnal surface layer and the residual layer aloft. In the present study, the well-known case of day 33 of the Wangara experiment is resimulated using the Weather Research and Forecasting (WRF) model in an idealized single-column mode to assess the performance of a frequently used planetary boundary layer (PBL) scheme, the Yonsei University (YSU) PBL scheme. These results are compared with two large eddy simulations (LES) for the same case study imposing different surface fluxes: one using previous surface fluxes calculated for the Wangara experiment and a second one using output from the WRF model. The results show a reasonable agreement of the PBL scheme in WRF with the LES. Overall, all the simulations presented a cold bias of ~3 Kelvin for the potential temperature and underestimation of the wind speed, especially after the transition to nighttime conditions (biases were up to 4 ms-1). Finally, an alternative set of eddy diffusivity equations was tested to represent the transition characteristics of a sunset period, with a stable layer below and a new parameterization for the convective decay regime typically observed in the RL aloft. This set of equations led to a gradual decrease of the eddy diffusivity, which replaces the instantaneous collapse of traditional diagnostics for eddy diffusivities. More appreciable changes were observed in air temperature, wind speed and specific humidity (up to 0.5 K, 0.6 ms-1, and 0

  18. About Merging Threshold and Critical Flux Concepts into a Single One: The Boundary Flux

    Directory of Open Access Journals (Sweden)

    Marco Stoller

    2014-01-01

    Full Text Available In the last decades much effort was put in understanding fouling phenomena on membranes. One successful approach to describe fouling issues on membranes is the critical flux theory. The possibility to measure a maximum value of the permeate flux for a given system without incurring in fouling issues was a breakthrough in membrane process design. However, in many cases critical fluxes were found to be very low, lower than the economic feasibility of the process. The knowledge of the critical flux value must be therefore considered as a good starting point for process design. In the last years, a new concept was introduced, the threshold flux, which defines the maximum permeate flow rate characterized by a low constant fouling rate regime. This concept, more than the critical flux, is a new practical tool for membrane process designers. In this paper a brief review on critical and threshold flux will be reported and analyzed. And since the concepts share many common aspects, merged into a new concept, called the boundary flux, the validation will occur by the analysis of previously collected data by the authors, during the treatment of olive vegetation wastewater by ultrafiltration and nanofiltration membranes.

  19. Single-phase liquid flow forced convection under a nearly uniform heat flux boundary condition in microchannels

    KAUST Repository

    Lee, Man

    2012-02-22

    A microchannel heat sink, integrated with pressure and temperature microsensors, is utilized to study single-phase liquid flow forced convection under a uniform heat flux boundary condition. Utilizing a waferbond-and-etch- back technology, the heat source, temperature and pressure sensors are encapsulated in a thin composite membrane capping the microchannels, thus allowing experimentally good control of the thermal boundary conditions. A three-dimensional physical model has been constructed to facilitate numerical simulations of the heat flux distribution. The results indicate that upstream the cold working fluid absorbs heat, while, within the current operating conditions, downstream the warmer working fluid releases heat. The Nusselt number is computed numerically and compared with experimental and analytical results. The wall Nusselt number in a microchannel can be estimated using classical analytical solutions only over a limited range of the Reynolds number, Re: both the top and bottom Nusselt numbers approach 4 for Re < 1, while the top and bottom Nusselt numbers approach 0 and 5.3, respectively, for Re > 100. The experimentally estimated Nusselt number for forced convection is highly sensitive to the location of the temperature measurements used in calculating the Nusselt number. © 2012 IOP Publishing Ltd.

  20. Improving Wind Predictions in the Marine Atmospheric Boundary Layer through Parameter Estimation in a Single-Column Model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jared A.; Hacker, Joshua P.; Delle Monache, Luca; Kosović, Branko; Clifton, Andrew; Vandenberghe, Francois; Rodrigo, Javier Sanz

    2016-12-14

    A current barrier to greater deployment of offshore wind turbines is the poor quality of numerical weather prediction model wind and turbulence forecasts over open ocean. The bulk of development for atmospheric boundary layer (ABL) parameterization schemes has focused on land, partly due to a scarcity of observations over ocean. The 100-m FINO1 tower in the North Sea is one of the few sources worldwide of atmospheric profile observations from the sea surface to turbine hub height. These observations are crucial to developing a better understanding and modeling of physical processes in the marine ABL. In this study, we use the WRF single column model (SCM), coupled with an ensemble Kalman filter from the Data Assimilation Research Testbed (DART), to create 100-member ensembles at the FINO1 location. The goal of this study is to determine the extent to which model parameter estimation can improve offshore wind forecasts.

  1. Essential loci in centromeric heterochromatin of Drosophila melanogaster. I: the right arm of chromosome 2.

    Science.gov (United States)

    Coulthard, Alistair B; Alm, Christina; Cealiac, Iulia; Sinclair, Don A; Honda, Barry M; Rossi, Fabrizio; Dimitri, Patrizio; Hilliker, Arthur J

    2010-06-01

    With the most recent releases of the Drosophila melanogaster genome sequences, much of the previously absent heterochromatic sequences have now been annotated. We undertook an extensive genetic analysis of existing lethal mutations, as well as molecular mapping and sequence analysis (using a candidate gene approach) to identify as many essential genes as possible in the centromeric heterochromatin on the right arm of the second chromosome (2Rh) of D. melanogaster. We also utilized available RNA interference lines to knock down the expression of genes in 2Rh as another approach to identifying essential genes. In total, we verified the existence of eight novel essential loci in 2Rh: CG17665, CG17683, CG17684, CG17883, CG40127, CG41265, CG42595, and Atf6. Two of these essential loci, CG41265 and CG42595, are synonymous with the previously characterized loci l(2)41Ab and unextended, respectively. The genetic and molecular analysis of the previously reported locus, l(2)41Ae, revealed that this is not a single locus, but rather it is a large region of 2Rh that extends from unextended (CG42595) to CG17665 and includes four of the novel loci uncovered here.

  2. Creep deformation-induced antiphase boundaries in L12-containing single-crystal cobalt-base superalloys

    International Nuclear Information System (INIS)

    Eggeler, Yolita M.; Titus, Michael S.; Suzuki, Akane; Pollock, Tresa M.

    2014-01-01

    Creep-induced antiphase boundaries (APBs) in new Co-base single-crystal superalloys with coherent embedded L1 2 -γ′ precipitates have been observed. APBs formed during single-crystal tensile creep tests performed at 900 °C under vacuum at stresses between 275 and 310 MPa. The alloys investigated contained 30–39 at.% Ni, which was added to the Co–Al–W ternary system to expand the γ–γ′ phase field and increase the γ′-solvus. Transmission electron microscopy (TEM) using two-beam conditions with fundamental and superlattice reflections was performed for defect characterization. The Burgers vector b of dislocations associated with the APBs was determined to be of type b = a 0 /2[011] and a 0 /2[011 ¯ ]. The displacement vectors, R, of the APBs matched the dislocation Burgers vectors, with R = b = a 0 /2[011]. APBs were observed in nearly every precipitate beyond 0.5% creep strain for the compositions investigated. The implications for high-temperature properties are discussed

  3. Retrotransposon-induced heterochromatin spreading in the mouse revealed by insertional polymorphisms.

    Directory of Open Access Journals (Sweden)

    Rita Rebollo

    2011-09-01

    Full Text Available The "arms race" relationship between transposable elements (TEs and their host has promoted a series of epigenetic silencing mechanisms directed against TEs. Retrotransposons, a class of TEs, are often located in repressed regions and are thought to induce heterochromatin formation and spreading. However, direct evidence for TE-induced local heterochromatin in mammals is surprisingly scarce. To examine this phenomenon, we chose two mouse embryonic stem (ES cell lines that possess insertionally polymorphic retrotransposons (IAP, ETn/MusD, and LINE elements at specific loci in one cell line but not the other. Employing ChIP-seq data for these cell lines, we show that IAP elements robustly induce H3K9me3 and H4K20me3 marks in flanking genomic DNA. In contrast, such heterochromatin is not induced by LINE copies and only by a minority of polymorphic ETn/MusD copies. DNA methylation is independent of the presence of IAP copies, since it is present in flanking regions of both full and empty sites. Finally, such spreading into genes appears to be rare, since the transcriptional start sites of very few genes are less than one Kb from an IAP. However, the B3galtl gene is subject to transcriptional silencing via IAP-induced heterochromatin. Hence, although rare, IAP-induced local heterochromatin spreading into nearby genes may influence expression and, in turn, host fitness.

  4. Cervantes and Quijote protect heterochromatin from aberrant recombination and lead the way to the nuclear periphery.

    Science.gov (United States)

    Ryu, Taehyun; Bonner, Melissa R; Chiolo, Irene

    2016-09-02

    Repairing double-strand breaks (DSBs) is particularly challenging in heterochromatin, where the abundance of repeated sequences exacerbates the risk of ectopic recombination and chromosome rearrangements. In Drosophila cells, faithful homologous recombination (HR) repair of heterochromatic DSBs relies on a specialized pathway that relocalizes repair sites to the nuclear periphery before Rad51 recruitment. Here we show that HR progression is initially blocked inside the heterochromatin domain by SUMOylation and the coordinated activity of two distinct Nse2 SUMO E3 ligases: Quijote (Qjt) and Cervantes (Cerv). In addition, the SUMO-targeted ubiquitin ligase (STUbL) Dgrn, but not its partner dRad60, is recruited to heterochromatic DSBs at early stages of repair and mediates relocalization. However, Dgrn is not required to prevent Rad51 recruitment inside the heterochromatin domain, suggesting that the block to HR progression inside the domain and relocalization to the nuclear periphery are genetically separable pathways. Further, SUMOylation defects affect relocalization without blocking heterochromatin expansion, revealing that expansion is not required for relocalization. Finally, nuclear pores and inner nuclear membrane proteins (INMPs) anchor STUbL/RENi components and repair sites to the nuclear periphery, where repair continues. Together, these studies reveal a critical role of SUMOylation and nuclear architecture in the spatial and temporal regulation of heterochromatin repair and the protection of genome integrity.

  5. Heterochromatin marks HP1γ, HP1α and H3K9me3, and DNA damage response activation in human testis development and germ cell tumours

    DEFF Research Database (Denmark)

    Bartkova, J; Moudry, P; Hodny, Z

    2011-01-01

    of germ cells vs. somatic tissues in early tumourigenesis. Conceptually interesting findings were that subsets of human cells in vivo proliferate despite enhanced heterochromatinization, and that cells can strongly express even multiple heterochromatin features in the absence of functional retinoblastoma...

  6. Effect of Low Angle Grain Boundaries on Mechanical Properties of DD5 Single Crystal Ni-base Superalloy

    Directory of Open Access Journals (Sweden)

    QIN Jianchao

    2017-06-01

    Full Text Available The effects of low angle grain boundaries on the mechanical properties of second generation single crystal superalloy DD5 were investigated and the test specimens were prepared by using seeds. The results show that at 870 ℃, the yield strength and breaking strength showed no difference when the angle is below 16.1°. The elongation is higher than 15% when the angle is below 11.4°, but the elongation decreases quickly when angle is above 11.4°. At 980 ℃/250 MPa, the rupture life is higher than 130 h when the angle is below 5.1°, and decreased slowly when the angle is above 5.1°. The rupture life still remaines 85% when the angle is 14.8°. But the rupture life decreases quickly when the angle is above 14.8°.At 1093 ℃/158 MPa, the rupture life is higher than 30 h when the angle is below 5.1°, and decreases when the angle is above 5.1°.

  7. Single grain boundary break junction for suspended nanogap electrodes with gapwidth down to 1-2 nm by focused ion beam milling.

    Science.gov (United States)

    Cui, Ajuan; Liu, Zhe; Dong, Huanli; Wang, Yujin; Zhen, Yonggang; Li, Wuxia; Li, Junjie; Gu, Changzhi; Hu, Wenping

    2015-05-20

    Single grain boundary junctions are used for the fabrication of suspended nanogap electrodes with a gapwidth down to 1-2 nm through the break of such junctions by focused ion beam (FIB) milling. With advantages of stability and no debris, such nanogap electrodes are suitable for single molecular electronic device construction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Comparative Genomic Analyses Provide New Insights into the Evolutionary Dynamics of Heterochromatin in Drosophila.

    Science.gov (United States)

    Caizzi, Ruggiero; Moschetti, Roberta; Piacentini, Lucia; Fanti, Laura; Marsano, Renè Massimiliano; Dimitri, Patrizio

    2016-08-01

    The term heterochromatin has been long considered synonymous with gene silencing, but it is now clear that the presence of transcribed genes embedded in pericentromeric heterochromatin is a conserved feature in the evolution of eukaryotic genomes. Several studies have addressed the epigenetic changes that enable the expression of genes in pericentric heterochromatin, yet little is known about the evolutionary processes through which this has occurred. By combining genome annotation analysis and high-resolution cytology, we have identified and mapped 53 orthologs of D. melanogaster heterochromatic genes in the genomes of two evolutionarily distant species, D. pseudoobscura and D. virilis. Our results show that the orthologs of the D. melanogaster heterochromatic genes are clustered at three main genomic regions in D. virilis and D. pseudoobscura. In D. virilis, the clusters lie in the middle of euchromatin, while those in D. pseudoobscura are located in the proximal portion of the chromosome arms. Some orthologs map to the corresponding Muller C element in D. pseudoobscura and D. virilis, while others localize on the Muller B element, suggesting that chromosomal rearrangements that have been instrumental in the fusion of two separate elements involved the progenitors of genes currently located in D. melanogaster heterochromatin. These results demonstrate an evolutionary repositioning of gene clusters from ancestral locations in euchromatin to the pericentromeric heterochromatin of descendent D. melanogaster chromosomes. Remarkably, in both D. virilis and D. pseudoobscura the gene clusters show a conserved association with the HP1a protein, one of the most highly evolutionarily conserved epigenetic marks. In light of these results, we suggest a new scenario whereby ancestral HP1-like proteins (and possibly other epigenetic marks) may have contributed to the evolutionary repositioning of gene clusters into heterochromatin.

  9. Nonlinear Boundary Value Problem for Concave Capillary Surfaces Occurring in Single Crystal Rod Growth from the Melt

    Directory of Open Access Journals (Sweden)

    Agneta Maria Balint

    2008-12-01

    Full Text Available The boundary value problem z″=((ρ⋅g⋅z−p/γ[1+(z′2]3/2−(1/r⋅[1+(z′2]⋅z′, r∈[r1, r0], z′(r1=−tan⁡(π/2−αg, z′(r0=−tan⁡αc, z(r0=0, and z(r is strictly decreasing on [r1,r0], is considered. Here, 0boundary value problem (NLBVP. Numerical illustration is given. This kind of results is useful in the experiment planning and technology design of single crystal rod growth from the melt by edge-defined film-fed growth (EFG method. With this aim, this study was undertaken.

  10. Characterization of rDNAs and Tandem Repeats in the Heterochromatin of Brassica rapa

    NARCIS (Netherlands)

    Lim, K.B.; Jong, de J.H.S.G.M.; Yang, T.J.; Park, J.Y.; Kwon, S.J.; Kim, J.S.; Lim, M.H.; Kim, J.A.; Jin, M.; Jin, Y.M.; Kim, S.H.; Lim, Y.P.; Bang, J.W.; Kim, H.I.; Park, B.S.

    2005-01-01

    We describe the morphology and molecular organization of heterochromatin domains in the interphase nuclei, and mitotic and meiotic chromosomes, of Brassica rapa, using DAPI staining and fluorescence in situ hybridization (FISH) of rDNA and pericentromere tandem repeats. We have developed a simple

  11. Mammalian HP1 Isoforms Have Specific Roles in Heterochromatin Structure and Organization

    Directory of Open Access Journals (Sweden)

    Laia Bosch-Presegué

    2017-11-01

    Full Text Available HP1 is a structural component of heterochromatin. Mammalian HP1 isoforms HP1α, HP1β, and HP1γ play different roles in genome stability, but their precise role in heterochromatin structure is unclear. Analysis of Hp1α−/−, Hp1β−/−, and Hp1γ−/− MEFs show that HP1 proteins have both redundant and unique functions within pericentric heterochromatin (PCH and also act globally throughout the genome. HP1α confines H4K20me3 and H3K27me3 to regions within PCH, while its absence results in a global hyper-compaction of chromatin associated with a specific pattern of mitotic defects. In contrast, HP1β is functionally associated with Suv4-20h2 and H4K20me3, and its loss induces global chromatin decompaction and an abnormal enrichment of CTCF in PCH and other genomic regions. Our work provides insight into the roles of HP1 proteins in heterochromatin structure and genome stability.

  12. Heterochromatin variation and LINE-1 distribution in Artibeus (Chiroptera, Phyllostomidae from Central Amazon, Brazil

    Directory of Open Access Journals (Sweden)

    Érica Martinha Silva de Souza

    2017-09-01

    Full Text Available Species in the subgenus Artibeus Leach, 1821 are widely distributed in Brazil. Conserved karyotypes characterize the group with identical diploid number and chromosome morphology. Recent studies suggested that the heterochromatin distribution and accumulation patterns can vary among species. In order to assess whether variation can also occur within species, we have analyzed the chromosomal distribution of constitutive heterochromatin in A. planirostris (Spix, 1823 and A. lituratus (Olfers, 1818 from Central Amazon (North Brazil and contrasted our findings with those reported for other localities in Brazil. In addition, Ag-NOR staining and FISH with 18S rDNA, telomeric, and LINE-1 probes were performed to assess the potential role that these different repetitive markers had in shaping the current architecture of heterochromatic regions. Both species presented interindividual variation of constitutive heterochromatin. In addition, in A. planirostris the centromeres of most chromosomes are enriched with LINE-1, colocated with pericentromeric heterochromatin blocks. Overall, our data indicate that amplification and differential distribution of the investigated repetitive DNAs might have played a significant role in shaping the chromosome architecture of the subgenus Artibeus.

  13. Alteration of terminal heterochromatin and chromosome rearrangements in derivatives of wheat-rye hybrids.

    Science.gov (United States)

    Fu, Shulan; Lv, Zhenling; Guo, Xiang; Zhang, Xiangqi; Han, Fangpu

    2013-08-20

    Wheat-rye addition and substitution lines and their self progenies revealed variations in telomeric heterochromatin and centromeres. Furthermore, a mitotically unstable dicentric chromosome and stable multicentric chromosomes were observed in the progeny of a Chinese Spring-Imperial rye 3R addition line. An unstable multicentric chromosome was found in the progeny of a 6R/6D substitution line. Drastic variation of terminal heterochromatin including movement and disappearance of terminal heterochromatin occurred in the progeny of wheat-rye addition line 3R, and the 5RS ditelosomic addition line. Highly stable minichromosomes were observed in the progeny of a monosomic 4R addition line, a ditelosomic 5RS addition line and a 6R/6D substitution line. Minichromosomes, with and without the FISH signals for telomeric DNA (TTTAGGG)n, derived from a monosomic 4R addition line are stable and transmissible to the next generation. The results indicated that centromeres and terminal heterochromatin can be profoundly altered in wheat-rye hybrid derivatives. Copyright © 2013. Published by Elsevier Ltd.

  14. Heterochromatin variation and LINE-1 distribution inArtibeus(Chiroptera, Phyllostomidae) from Central Amazon, Brazil.

    Science.gov (United States)

    de Souza, Érica Martinha Silva; Gross, Maria Claudia; Silva, Carlos Eduardo Faresin E; Sotero-Caio, Cibele Gomes; Feldberg, Eliana

    2017-01-01

    Species in the subgenus Artibeus Leach, 1821 are widely distributed in Brazil. Conserved karyotypes characterize the group with identical diploid number and chromosome morphology. Recent studies suggested that the heterochromatin distribution and accumulation patterns can vary among species. In order to assess whether variation can also occur within species, we have analyzed the chromosomal distribution of constitutive heterochromatin in A. planirostris (Spix, 1823) and A. lituratus (Olfers, 1818) from Central Amazon (North Brazil) and contrasted our findings with those reported for other localities in Brazil. In addition, Ag-NOR staining and FISH with 18S rDNA, telomeric, and LINE-1 probes were performed to assess the potential role that these different repetitive markers had in shaping the current architecture of heterochromatic regions. Both species presented interindividual variation of constitutive heterochromatin. In addition, in A. planirostris the centromeres of most chromosomes are enriched with LINE-1, colocated with pericentromeric heterochromatin blocks. Overall, our data indicate that amplification and differential distribution of the investigated repetitive DNAs might have played a significant role in shaping the chromosome architecture of the subgenus Artibeus.

  15. Heterochromatin protein 1 is recruited to various types of DNA damage

    NARCIS (Netherlands)

    Luijsterburg, Martijn S.; Dinant, Christoffel; Lans, Hannes; Stap, Jan; Wiernasz, Elzbieta; Lagerwerf, Saskia; Warmerdam, Daniël O.; Lindh, Michael; Brink, Maartje C.; Dobrucki, Jurek W.; Aten, Jacob A.; Fousteri, Maria I.; Jansen, Gert; Dantuma, Nico P.; Vermeulen, Wim; Mullenders, Leon H. F.; Houtsmuller, Adriaan B.; Verschure, Pernette J.; van Driel, Roel

    2009-01-01

    Heterochromatin protein 1 (HP1) family members are chromatin-associated proteins involved in transcription, replication, and chromatin organization. We show that HP1 isoforms HP1-alpha, HP1-beta, and HP1-gamma are recruited to ultraviolet (UV)-induced DNA damage and double-strand breaks (DSBs) in

  16. Molecular structures of centromeric heterochromatin and karyotypic evolution in the Siamese crocodile (Crocodylus siamensis) (Crocodylidae, Crocodylia).

    Science.gov (United States)

    Kawagoshi, Taiki; Nishida, Chizuko; Ota, Hidetoshi; Kumazawa, Yoshinori; Endo, Hideki; Matsuda, Yoichi

    2008-01-01

    Crocodilians have several unique karyotypic features, such as small diploid chromosome numbers (30-42) and the absence of dot-shaped microchromosomes. Of the extant crocodilian species, the Siamese crocodile (Crocodylus siamensis) has no more than 2n = 30, comprising mostly bi-armed chromosomes with large centromeric heterochromatin blocks. To investigate the molecular structures of C-heterochromatin and genomic compartmentalization in the karyotype, characterized by the disappearance of tiny microchromosomes and reduced chromosome number, we performed molecular cloning of centromeric repetitive sequences and chromosome mapping of the 18S-28S rDNA and telomeric (TTAGGG)( n ) sequences. The centromeric heterochromatin was composed mainly of two repetitive sequence families whose characteristics were quite different. Two types of GC-rich CSI-HindIII family sequences, the 305 bp CSI-HindIII-S (G+C content, 61.3%) and 424 bp CSI-HindIII-M (63.1%), were localized to the intensely PI-stained centric regions of all chromosomes, except for chromosome 2 with PI-negative heterochromatin. The 94 bp CSI-DraI (G+C content, 48.9%) was tandem-arrayed satellite DNA and localized to chromosome 2 and four pairs of small-sized chromosomes. The chromosomal size-dependent genomic compartmentalization that is supposedly unique to the Archosauromorpha was probably lost in the crocodilian lineage with the disappearance of microchromosomes followed by the homogenization of centromeric repetitive sequences between chromosomes, except for chromosome 2.

  17. Super-Resolution Localization Microscopy of γ-H2AX and Heterochromatin after Folate Deficiency.

    Science.gov (United States)

    Bach, Margund; Savini, Claudia; Krufczik, Matthias; Cremer, Christoph; Rösl, Frank; Hausmann, Michael

    2017-08-08

    Folate is an essential water-soluble vitamin in food and nutrition supplements. As a one-carbon source, it is involved in many central regulatory processes, such as DNA, RNA, and protein methylation as well as DNA synthesis and repair. Deficiency in folate is considered to be associated with an increased incidence of several malignancies, including cervical cancer that is etiologically linked to an infection with "high-risk" human papilloma viruses (HPV). However, it is still not known how a recommended increase in dietary folate after its deprivation affects the physiological status of cells. To study the impact of folate depletion and its subsequent reconstitution in single cells, we used quantitative chromatin conformation measurements obtained by super-resolution fluorescence microscopy, i.e., single molecule localization microscopy (SMLM). As a read-out, we examined the levels and the (re)positioning of γ-H2AX tags and histone H3K9me3 heterochromatin tags after immunostaining in three-dimensional (3D)-conserved cell nuclei. As model, we used HPV16 positive immortalized human keratinocytes that were cultivated under normal, folate deficient, and reconstituted conditions for different periods of time. The results were compared to cells continuously cultivated in standard folate medium. After 13 weeks in low folate, an increase in the phosphorylation of the histone H2AX was noted, indicative of an accumulation of DNA double strand breaks. DNA repair activity represented by the formation of those γ-H2AX clusters was maintained during the following 15 weeks of examination. However, the clustered arrangements of tags appeared to relax in a time-dependent manner. Parallel to the repair activity, the chromatin methylation activity increased as detected by H3K9me3 tags. The progress of DNA double strand repair was accompanied by a reduction of the detected nucleosome density around the γ-H2AX clusters, suggesting a shift from hetero- to euchromatin to allow access

  18. Sensitivity analysis of stress state and bond strength of fiber-reinforced polymer/concrete interface to boundary conditions in single shear pull-out test

    Directory of Open Access Journals (Sweden)

    Tayyebeh Mohammadi

    2015-05-01

    Full Text Available The bond between fiber-reinforced polymer and concrete substrate plays a key role in the performance of concrete structures after strengthened by externally bonded fiber-reinforced polymer composite materials. The single shear pull-out test is generally used to determine the interface characteristics, and various bond–slip models have been proposed based on the results of this test. However, the sensitivity of the bond strength to the boundary conditions has not yet been considered in the available models in the literatures. This article presents an experimental and numerical study targeted at understanding the influence of the boundary conditions on the bond strength of the fiber-reinforced polymer/concrete interface in the single shear pull-out test. The validated finite element analysis by experimental results is used for the sensitivity study of the bond strength and stress state of the interface to the boundary conditions of the concrete block. It is found that the constraint height of the concrete block at the loaded side is an influential parameter on the stress state of the interface and the bond strength.

  19. Sirt7 stabilizes rDNA heterochromatin through recruitment of DNMT1 and Sirt1.

    Science.gov (United States)

    Ianni, Alessandro; Hoelper, Soraya; Krueger, Marcus; Braun, Thomas; Bober, Eva

    2017-10-21

    Maintenance of highly compact heterochromatin at ribosomal DNA (rDNA) segments is essential to prevent homologous recombination between rDNA repeats and for preserving genomic stability and nucleolar architecture. Here, we investigated the role of Sirtuin 7 (Sirt7) in the regulation of rDNA chromatin structure, rDNA repeat stability and nucleolar organization. We found that Sirt7 mediates heterochromatin formation at rRNA genes through recruitment of DNA methyltransferase 1 and another member of the sirtuin family, Sirt1. Lack of Sirt7 leads to nucleolar fragmentation associated with hypomethylation of rDNA and hyperacetylation of histones at rDNA loci resulting in rDNA and genomic instability. Our findings suggest a novel role of Sirt7 in preventing cellular transformation by mediating maintenance of rDNA repeats and nucleolar integrity. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Expression and chromatin structures of cellulolytic enzyme gene regulated by heterochromatin protein 1

    OpenAIRE

    Zhang, Xiujun; Qu, Yinbo; Qin, Yuqi

    2016-01-01

    Background Heterochromatin protein 1 (HP1, homologue HepA in Penicillium oxalicum) binding is associated with a highly compact chromatin state accompanied by gene silencing or repression. HP1 loss leads to the derepression of gene expression. We investigated HepA roles in regulating cellulolytic enzyme gene expression, as an increasingly number of studies have suggested that cellulolytic enzyme gene expression is not only regulated by transcription factors, but is also affected by the chromat...

  1. Amplification of a GC-rich heterochromatin in the freshwater fish Leporinus desmotes (Characiformes, Anostomidae

    Directory of Open Access Journals (Sweden)

    Vladimir Pavan Margarido

    2000-09-01

    Full Text Available This is the first description of the karyotype of Leporinus desmotes. The diploid female number was 2n = 54 meta- and submetacentric chromosomes. The nucleolar organizing regions (NORs were studied by silver nitrate staining and rDNA fluorescence in situ hybridization (FISH and were found to be located in the telomeric region of the long arm of the 9th pair. C-banding revealed centromeric and telomeric heterochromatin segments in most chromosomes. Intercalar blocks of heterochromatin were observed in the long arm of six chromosome pairs. Besides a NOR-adjacent heterochromatin, all of the intercalar heterochromatic segments were brightly fluorescent by mithramycin staining. These data suggest that a unique amplification of a primordial GC-rich heterochromatin, probably NOR-associated, may have taken place in the karyotype diversification of this Leporinus species.Esta é a primeira descrição do cariótipo de Leporinus desmotes fêmea. O número diplóide encontrado foi 2n = 54 cromossomos meta- e submetacêntricos. As regiões organizadoras de nucléolos (NORs foram estudadas através da impregnação pela prata e por hibridização in situ com sondas de DNAr (FISH, e foram localizadas na região telomérica do braço longo do 9º par. Heterocromatinas centromérica e telomérica foram reveladas pelo bandamento C na maioria dos cromossomos. Adicionalmente, grande quantidade de heterocromatina intercalar ou subtelomérica foi também observada. Diferenciação composicional na maior parte da heterocromatina identificada em L. desmotes pode ser inferida através da coloração pela mitramicina, caracterizando um caso peculiar de amplificação de segmentos heterocromáticos ricos em bases GC neste grupo de peixes.

  2. Hidden heterochromatin: characterization in the Rodentia species Cricetus cricetus, Peromyscus eremicus (Cricetidae and Praomys tullbergi (Muridae

    Directory of Open Access Journals (Sweden)

    Ana Paço

    2009-01-01

    Full Text Available The use of in situ restriction endonuclease (RE (which cleaves DNA at specific sequences digestion has proven to be a useful technique in improving the dissection of constitutive heterochromatin (CH, and in the understanding of the CH evolution in different genomes. In the present work we describe in detail the CH of the three Rodentia species, Cricetus cricetus, Peromyscus eremicus (family Cricetidae and Praomys tullbergi (family Muridae using a panel of seven REs followed by C-banding. Comparison of the amount, distribution and molecular nature of C-positive heterochromatin revealed molecular heterogeneity in the heterochromatin of the three species. The large number of subclasses of CH identified in Praomys tullbergi chromosomes indicated that the karyotype of this species is the more derived when compared with the other two genomes analyzed, probably originated by a great number of complex chromosomal rearrangements. The high level of sequence heterogeneity identified in the CH of the three genomes suggests the coexistence of different satellite DNA families, or variants of these families in these genomes.

  3. A new first-order turbulence mixing model for the stable atmospheric boundary-layer: development and testing in large-eddy and single column models

    Science.gov (United States)

    Huang, J.; Bou-Zeid, E.; Golaz, J.

    2011-12-01

    Parameterization of the stably-stratified atmospheric boundary-layer is of crucial importance to different aspects of numerical weather prediction at regional scales and climate modeling at global scales, such as land-surface temperature forecasts, fog and frost prediction, and polar climate. It is well-known that most operational climate models require excessive turbulence mixing of the stable boundary-layer to prevent decoupling of the atmospheric component from the land component under strong stability, but the performance of such a model is unlikely to be satisfactory under weakly and moderately stable conditions. In this study we develop and test a general turbulence mixing model of the stable boundary-layer which works under different stabilities and for steady as well as unsteady conditions. A-priori large-eddy simulation (LES) tests are presented to motivate and verify the new parameterization. Subsequently, an assessment of this model using the GFDL single-column model (SCM) is performed. Idealized test cases including continuously varying stability, as well as stability discontinuity, are used to test the new SCM against LES results. A good match of mean and flux profiles is found when the new parameterization is used, while other traditional first-order turbulence models using the concept of stability function perform poorly. SCM spatial resolution is also found to have little impact on the performance of the new turbulence closure, but temporal resolution is important and a numerical stability criterion based on the model time step is presented.

  4. Bulk Single Crystal-Like Structural and Magnetic Characteristics of Epitaxial Spinel Ferrite Thin Films with Elimination of Antiphase Boundaries.

    Science.gov (United States)

    Singh, Amit V; Khodadadi, Behrouz; Mohammadi, Jamileh Beik; Keshavarz, Sahar; Mewes, Tim; Negi, Devendra Singh; Datta, Ranjan; Galazka, Zbigniew; Uecker, Reinhard; Gupta, Arunava

    2017-08-01

    Spinel ferrite NiFe 2 O 4 thin films have been grown on three isostructural substrates, MgAl 2 O 4 , MgGa 2 O 4 , and CoGa 2 O 4 using pulsed laser deposition. These substrates have lattice mismatches of 3.1%, 0.8%, and 0.2%, respectively, with NiFe 2 O 4 . As expected, the films grown on MgAl 2 O 4 substrate show the presence of the antiphase boundary defects. However, no antiphase boundaries (APBs) are observed for films grown on near-lattice-matched substrates MgGa 2 O 4 and CoGa 2 O 4 . This demonstrates that by using isostructural and lattice-matched substrates, the formation of APBs can be avoided in NiFe 2 O 4 thin films. Consequently, static and dynamic magnetic properties comparable with the bulk can be realized. Initial results indicate similar improvements in film quality and magnetic properties due to the elimination of APBs in other members of the spinel ferrite family, such as Fe 3 O 4 and CoFe 2 O 4 , which have similar crystallographic structure and lattice constants as NiFe 2 O 4 . © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Positive selection drives the evolution of rhino, a member of the heterochromatin protein 1 family in Drosophila.

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    Danielle Vermaak

    2005-07-01

    Full Text Available Heterochromatin comprises a significant component of many eukaryotic genomes. In comparison to euchromatin, heterochromatin is gene poor, transposon rich, and late replicating. It serves many important biological roles, from gene silencing to accurate chromosome segregation, yet little is known about the evolutionary constraints that shape heterochromatin. A complementary approach to the traditional one of directly studying heterochromatic DNA sequence is to study the evolution of proteins that bind and define heterochromatin. One of the best markers for heterochromatin is the heterochromatin protein 1 (HP1, which is an essential, nonhistone chromosomal protein. Here we investigate the molecular evolution of five HP1 paralogs present in Drosophila melanogaster. Three of these paralogs have ubiquitous expression patterns in adult Drosophila tissues, whereas HP1D/rhino and HP1E are expressed predominantly in ovaries and testes respectively. The HP1 paralogs also have distinct localization preferences in Drosophila cells. Thus, Rhino localizes to the heterochromatic compartment in Drosophila tissue culture cells, but in a pattern distinct from HP1A and lysine-9 dimethylated H3. Using molecular evolution and population genetic analyses, we find that rhino has been subject to positive selection in all three domains of the protein: the N-terminal chromo domain, the C-terminal chromo-shadow domain, and the hinge region that connects these two modules. Maximum likelihood analysis of rhino sequences from 20 species of Drosophila reveals that a small number of residues of the chromo and shadow domains have been subject to repeated positive selection. The rapid and positive selection of rhino is highly unusual for a gene encoding a chromosomal protein and suggests that rhino is involved in a genetic conflict that affects the germline, belying the notion that heterochromatin is simply a passive recipient of "junk DNA" in eukaryotic genomes.

  6. Comparative Heterochromatin Profiling Reveals Conserved and Unique Epigenome Signatures Linked to Adaptation and Development of Malaria Parasites.

    Science.gov (United States)

    Fraschka, Sabine A; Filarsky, Michael; Hoo, Regina; Niederwieser, Igor; Yam, Xue Yan; Brancucci, Nicolas M B; Mohring, Franziska; Mushunje, Annals T; Huang, Ximei; Christensen, Peter R; Nosten, Francois; Bozdech, Zbynek; Russell, Bruce; Moon, Robert W; Marti, Matthias; Preiser, Peter R; Bártfai, Richárd; Voss, Till S

    2018-03-14

    Heterochromatin-dependent gene silencing is central to the adaptation and survival of Plasmodium falciparum malaria parasites, allowing clonally variant gene expression during blood infection in humans. By assessing genome-wide heterochromatin protein 1 (HP1) occupancy, we present a comprehensive analysis of heterochromatin landscapes across different Plasmodium species, strains, and life cycle stages. Common targets of epigenetic silencing include fast-evolving multi-gene families encoding surface antigens and a small set of conserved HP1-associated genes with regulatory potential. Many P. falciparum heterochromatic genes are marked in a strain-specific manner, increasing the parasite's adaptive capacity. Whereas heterochromatin is strictly maintained during mitotic proliferation of asexual blood stage parasites, substantial heterochromatin reorganization occurs in differentiating gametocytes and appears crucial for the activation of key gametocyte-specific genes and adaptation of erythrocyte remodeling machinery. Collectively, these findings provide a catalog of heterochromatic genes and reveal conserved and specialized features of epigenetic control across the genus Plasmodium. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  7. Phylogenomic analysis reveals dynamic evolutionary history of the Drosophila heterochromatin protein 1 (HP1 gene family.

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    Mia T Levine

    Full Text Available Heterochromatin is the gene-poor, satellite-rich eukaryotic genome compartment that supports many essential cellular processes. The functional diversity of proteins that bind and often epigenetically define heterochromatic DNA sequence reflects the diverse functions supported by this enigmatic genome compartment. Moreover, heterogeneous signatures of selection at chromosomal proteins often mirror the heterogeneity of evolutionary forces that act on heterochromatic DNA. To identify new such surrogates for dissecting heterochromatin function and evolution, we conducted a comprehensive phylogenomic analysis of the Heterochromatin Protein 1 gene family across 40 million years of Drosophila evolution. Our study expands this gene family from 5 genes to at least 26 genes, including several uncharacterized genes in Drosophila melanogaster. The 21 newly defined HP1s introduce unprecedented structural diversity, lineage-restriction, and germline-biased expression patterns into the HP1 family. We find little evidence of positive selection at these HP1 genes in both population genetic and molecular evolution analyses. Instead, we find that dynamic evolution occurs via prolific gene gains and losses. Despite this dynamic gene turnover, the number of HP1 genes is relatively constant across species. We propose that karyotype evolution drives at least some HP1 gene turnover. For example, the loss of the male germline-restricted HP1E in the obscura group coincides with one episode of dramatic karyotypic evolution, including the gain of a neo-Y in this lineage. This expanded compendium of ovary- and testis-restricted HP1 genes revealed by our study, together with correlated gain/loss dynamics and chromosome fission/fusion events, will guide functional analyses of novel roles supported by germline chromatin.

  8. Deacetylation of H4-K16Ac and heterochromatin assembly in senescence

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    Contrepois Kévin

    2012-08-01

    Full Text Available Abstract Background Cellular senescence is a stress response of mammalian cells leading to a durable arrest of cell proliferation that has been implicated in tumor suppression, wound healing, and aging. The proliferative arrest is mediated by transcriptional repression of genes essential for cell division by the retinoblastoma protein family. This repression is accompanied by varying degrees of heterochromatin assembly, but little is known regarding the molecular mechanisms involved. Results We found that both deacetylation of H4-K16Ac and expression of HMGA1/2 can contribute to DNA compaction during senescence. SIRT2, an NAD-dependent class III histone deacetylase, contributes to H4-K16Ac deacetylation and DNA compaction in human fibroblast cell lines that assemble striking senescence-associated heterochromatin foci (SAHFs. Decreased H4-K16Ac was observed in both replicative and oncogene-induced senescence of these cells. In contrast, this mechanism was inoperative in a fibroblast cell line that did not assemble extensive heterochromatin during senescence. Treatment of senescent cells with trichostatin A, a class I/II histone deacetylase inhibitor, also induced rapid and reversible decondensation of SAHFs. Inhibition of DNA compaction did not significantly affect the stability of the senescent state. Conclusions Variable DNA compaction observed during senescence is explained in part by cell-type specific regulation of H4 deacetylation and HMGA1/2 expression. Deacetylation of H4-K16Ac during senescence may explain reported decreases in this mark during mammalian aging and in cancer cells.

  9. ICBP90, a Novel Methyl K9 H3 Binding Protein Linking Protein Ubiquitination with Heterochromatin Formation▿

    Science.gov (United States)

    Karagianni, Panagiota; Amazit, Larbi; Qin, Jun; Wong, Jiemin

    2008-01-01

    Methylation of histone H3 on lysine 9 is critical for diverse biological processes including transcriptional repression, heterochromatin formation, and X inactivation. The biological effects of histone methylation are thought to be mediated by effector proteins that recognize and bind to specific patterns of methylation. Using an unbiased in vitro biochemical approach, we have identified ICBP90, a transcription and cell cycle regulator, as a novel methyl K9 H3-specific binding protein. ICBP90 and its murine homologue Np95 are enriched in pericentric heterochromatin of interphase nuclei, and this localization is dependent on H3K9 methylation. Specific binding of ICBP90 to methyl K9 H3 depends on two functional domains, a PHD (plant homeodomain) finger that defines the binding specificity and an SRA (SET- and RING-associated) domain that promotes binding activity. Furthermore, we present evidence that ICBP90 is required for proper heterochromatin formation in mammalian cells. PMID:17967883

  10. ICBP90, a novel methyl K9 H3 binding protein linking protein ubiquitination with heterochromatin formation.

    Science.gov (United States)

    Karagianni, Panagiota; Amazit, Larbi; Qin, Jun; Wong, Jiemin

    2008-01-01

    Methylation of histone H3 on lysine 9 is critical for diverse biological processes including transcriptional repression, heterochromatin formation, and X inactivation. The biological effects of histone methylation are thought to be mediated by effector proteins that recognize and bind to specific patterns of methylation. Using an unbiased in vitro biochemical approach, we have identified ICBP90, a transcription and cell cycle regulator, as a novel methyl K9 H3-specific binding protein. ICBP90 and its murine homologue Np95 are enriched in pericentric heterochromatin of interphase nuclei, and this localization is dependent on H3K9 methylation. Specific binding of ICBP90 to methyl K9 H3 depends on two functional domains, a PHD (plant homeodomain) finger that defines the binding specificity and an SRA (SET- and RING-associated) domain that promotes binding activity. Furthermore, we present evidence that ICBP90 is required for proper heterochromatin formation in mammalian cells.

  11. Cytogenetics of Melitoma segmentaria (Fabricius, 1804) (Hymenoptera, Apidae) reveals differences in the characteristics of heterochromatin in bees.

    Science.gov (United States)

    Cristiano, Maykon Passos; Simões, Talitta Guimarães; Lopes, Denilce Meneses; Pompolo, Silvia das Graças

    2014-01-01

    To date, more than 65 species of Brazilian bees (of the superfamily Apoidea) have been cytogenetically studied, but only a few solitary species have been analyzed. One example is the genus Melitoma Lepeletier & Serville, 1828, for which there is no report in the literature with regard to cytogenetic studies. The objective of the present study is to analyze the chromosome number and morphology of the species Melitoma segmentaria (Fabricius, 1804), as well as to determine the pattern of heterochromatin distribution and identify the adenine-thymine (AT)- and guanine-cytosine (GC)-rich regions. Melitoma segmentaria presents chromosome numbers of 2n=30 (females) and n=15 (males). With C-banding, it is possible to classify the chromosomes into seven pseudo-acrocentric pairs (A(M)), seven pseudo-acrocentric pairs with interstitial heterochromatin (A(Mi)), and one totally heterochromatic metacentric pair (M(h)). Fluorochrome staining has revealed that heterochromatin present in the chromosomal arms is rich in GC base pairs (CMA3 (+)) and the centromeric region is rich in AT base pairs (DAPI(+)). The composition found for Melitoma diverges from the pattern observed in other bees, in which the heterochromatin is usually rich in AT. In bees, few heterochromatic regions are rich in GC and these are usually associated with or localized close to the nucleolus organizer regions (NORs). Silver nitrate impregnation marks the heterochromatin present in the chromosome arms, which makes identification of the NOR in the chromosomes impossible. As this technique reveals proteins in the NOR, the observation that is made in the present study suggests that the proteins found in the heterochromatin are qualitatively similar to those in the NOR.

  12. The molecular basis for stability of heterochromatin-mediated silencing in mammals

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    Hiragami-Hamada Kyoko

    2009-11-01

    Full Text Available Abstract The archetypal epigenetic phenomenon of position effect variegation (PEV in Drosophila occurs when a gene is brought abnormally close to heterochromatin, resulting in stochastic silencing of the affected gene in a proportion of cells that would normally express it. PEV has been instrumental in unraveling epigenetic mechanisms. Using an in vivo mammalian model for PEV we have extensively investigated the molecular basis for heterochromatin-mediated gene silencing. Here we distinguish 'epigenetic effects' from other cellular differences by studying ex vivo cells that are identical, apart from the expression of the variegating gene which is silenced in a proportion of the cells. By separating cells according to transgene expression we show here that silencing appears to be associated with histone H3 lysine 9 trimethylation (H3K9me3, DNA methylation and the localization of the silenced gene to a specific nuclear compartment enriched in these modifications. In contrast, histone H3 acetylation (H3Ac and lysine 4 di or tri methylation (H3K4me2/3 are the predominant modifications associated with expression where we see the gene in a euchromatic compartment. Interestingly, DNA methylation and inaccessibility, rather than H3K9me3, correlated most strongly with resistance to de-repression by cellular activation. These results have important implications for understanding the contribution of specific factors involved in the establishment and maintenance of gene silencing and activation in vivo.

  13. Facultative heterochromatin formation at the IL-1 beta promoter in LPS tolerance and sepsis.

    Science.gov (United States)

    Yoza, Barbara K; McCall, Charles E

    2011-02-01

    The clinical phenotype in sepsis that is observed as LPS tolerance is determined by silencing of pro-inflammatory genes like IL-1 beta (IL-1β). This study shows that facultative heterochromatin (fHC) silences IL-1β expression during sepsis, where we find dephosphorylated histone H3 serine 10 and increased binding of heterochromatin protein-1 (HP-1) to the promoter. In both human sepsis blood leukocytes and an LPS tolerant human THP-1 cell model, we show that IκBα and v-rel reticuloendotheliosis viral oncogene homolog B (RelB) function as dominant labile mediators of fHC formation at the IL-1β promoter. Protein synthesis inhibition decreases levels of IκBα and RelB, converts silent fHC to euchromatin, and restores IL-1β transcription. We further show TLR dependent NFκB p65 and histone H3 serine 10 phosphorylation binding at the promoter. We conclude that the resolution phase of sepsis, which correlates with survival in humans, may depend on the plasticity of chromatin structure as found in fHC. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Heterochromatin base pair composition and diversification in holocentric chromosomes of kissing bugs (Hemiptera, Reduviidae)

    Science.gov (United States)

    Bardella, Vanessa Bellini; Pita, Sebastián; Vanzela, André Luis Laforga; Galvão, Cleber; Panzera, Francisco

    2016-01-01

    The subfamily Triatominae (Hemiptera, Reduviidae) includes 150 species of blood-sucking insects, vectors of Chagas disease or American trypanosomiasis. Karyotypic information reveals a striking stability in the number of autosomes. However, this group shows substantial variability in genome size, the amount and distribution of C-heterochromatin, and the chromosome positions of 45S rDNA clusters. Here, we analysed the karyotypes of 41 species from six different genera with C-fluorescence banding in order to evaluate the base-pair richness of heterochromatic regions. Our results show a high heterogeneity in the fluorescent staining of the heterochromatin in both autosomes and sex chromosomes, never reported before within an insect subfamily with holocentric chromosomes. This technique allows a clear discrimination of the heterochromatic regions classified as similar by C-banding, constituting a new chromosome marker with taxonomic and evolutionary significance. The diverse fluorescent patterns are likely due to the amplification of different repeated sequences, reflecting an unusual dynamic rearrangement in the genomes of this subfamily. Further, we discuss the evolution of these repeated sequences in both autosomes and sex chromosomes in species of Triatominae. PMID:27759763

  15. Karyotype, constitutive heterochromatin and nucleolar organizer regions (NORs in Belosacris coccineipes (Acrididae-Leptysminae

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    Loreto Vilma

    2000-01-01

    Full Text Available Several techniques including C-banding, fluorochromes and silver staining were used to obtain information about heterochromatin patterns in the grasshopper B. coccineipes. Conventional staining showed a karyotype with 2n = 23 chromosomes in males and 2n = 24 in females, as well as XO:XX sex determination and acrotelocentric chromosomes. The medium-sized X chromosome was heteropycnotic positive at the beginning of prophase I and negative in metaphase I. C-banding revealed heterochromatic blocks in the pericentromeric regions of all chromosomes. Silver nitrate staining in this species showed three small bivalents (S9-S11 as nucleolar organizers with NORs located in the pericentromeric regions. CMA3-positive blocks were seen in pericentromeric regions of pairs M6, S9, S10 and S11. Sequential staining with CMA3/AgNO3 revealed homology between the CMA3-positive bands and NORs of the bivalents S9, S10 and S11. The CMA3-positive block of the bivalent M6 could represent a latent secondary NOR. The results obtained permit us to distinguish two categories of the constitutive heterochromatin in B. coccineipes.

  16. Heterochromatin base pair composition and diversification in holocentric chromosomes of kissing bugs (Hemiptera, Reduviidae

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    Vanessa Bellini Bardella

    Full Text Available The subfamily Triatominae (Hemiptera, Reduviidae includes 150 species of blood-sucking insects, vectors of Chagas disease or American trypanosomiasis. Karyotypic information reveals a striking stability in the number of autosomes. However, this group shows substantial variability in genome size, the amount and distribution of C-heterochromatin, and the chromosome positions of 45S rDNA clusters. Here, we analysed the karyotypes of 41 species from six different genera with C-fluorescence banding in order to evaluate the base-pair richness of heterochromatic regions. Our results show a high heterogeneity in the fluorescent staining of the heterochromatin in both autosomes and sex chromosomes, never reported before within an insect subfamily with holocentric chromosomes. This technique allows a clear discrimination of the heterochromatic regions classified as similar by C-banding, constituting a new chromosome marker with taxonomic and evolutionary significance. The diverse fluorescent patterns are likely due to the amplification of different repeated sequences, reflecting an unusual dynamic rearrangement in the genomes of this subfamily. Further, we discuss the evolution of these repeated sequences in both autosomes and sex chromosomes in species of Triatominae.

  17. Temozolomide and carmustine cause large-scale heterochromatin reorganization in glioma cells.

    Science.gov (United States)

    Papait, Roberto; Magrassi, Lorenzo; Rigamonti, Dorotea; Cattaneo, Elena

    2009-02-06

    Temozolomide (TMZ) and carmustine (BCNU), cancer-drugs usually used in the treatment of gliomas, are DNA-methylating agents producing O6-methylguanine. It has been shown that 06-methylguanine triggers DNA mismatch repair and in turn induce apoptosis and senescence, respectively, over a 4 and 6 days period [Y. Hirose, M.S. Berger, R.O. Pieper, p53 effects both the duration of G2/M arrest and the fate of temozolomide-treated human glioblastoma cells, Cancer Res. 61 (2001) 1957-1963; W. Roos, M. Baumgartner, B. Kaina, Apoptosis triggered by DNA damage O6-methylguanine in human lymphocytes requires DNA replication and is mediated by p53 and Fas/CD95/Apo-1, Oncogene 23 (2004) 359-367]. Here we show that TMZ and BCNU have an earlier effect on nuclear organization and chromatin structure. In particular, we report that TMZ and BCNU induce clustering of pericentromeric heterochromatin regions and increase the amount of heterochromatic proteins MeCP2 and HP1alpha bound to chromatin. These drugs also decrease global levels of histone H3 acetylation and increase levels of histone H3 trimethylated on lysine 9 (H3-triMeK9). These events precede the senescence status. We conclude that TMZ and BCNU efficacy in glioma treatment may implicate a first event characterized by changes in heterochromatin organization and its silencing which is then followed by apoptosis and senescence.

  18. Temozolomide and carmustine cause large-scale heterochromatin reorganization in glioma cells

    International Nuclear Information System (INIS)

    Papait, Roberto; Magrassi, Lorenzo; Rigamonti, Dorotea; Cattaneo, Elena

    2009-01-01

    Temozolomide (TMZ) and carmustine (BCNU), cancer-drugs usually used in the treatment of gliomas, are DNA-methylating agents producing O6-methylguanine. It has been shown that 06-methylguanine triggers DNA mismatch repair and in turn induce apoptosis and senescence, respectively, over a 4 and 6 days period [Y. Hirose, M.S. Berger, R.O. Pieper, p53 effects both the duration of G2/M arrest and the fate of temozolomide-treated human glioblastoma cells, Cancer Res. 61 (2001) 1957-1963; W. Roos, M. Baumgartner, B. Kaina, Apoptosis triggered by DNA damage O6-methylguanine in human lymphocytes requires DNA replication and is mediated by p53 and Fas/CD95/Apo-1, Oncogene 23 (2004) 359-367]. Here we show that TMZ and BCNU have an earlier effect on nuclear organization and chromatin structure. In particular, we report that TMZ and BCNU induce clustering of pericentromeric heterochromatin regions and increase the amount of heterochromatic proteins MeCP2 and HP1α bound to chromatin. These drugs also decrease global levels of histone H3 acetylation and increase levels of histone H3 trimethylated on lysine 9 (H3-triMeK9). These events precede the senescence status. We conclude that TMZ and BCNU efficacy in glioma treatment may implicate a first event characterized by changes in heterochromatin organization and its silencing which is then followed by apoptosis and senescence.

  19. Cytogenetic analysis of Astylus antis (Perty, 1830 (Coleoptera, Melyridae: Karyotype, heterochromatin and location of ribosomal genes

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    Ernani de Oliveira Mendes-Neto

    2010-01-01

    Full Text Available Cytogenetic analysis of Astylus antis using mitotic and meiotic cells was performed to characterize the haploid and diploid numbers, sex determination system, chromosome morphology, constitutive heterochromatin distribution pattern and chromosomes carrying nucleolus organizer regions (NORs. Analysis of spermatogonial metaphase cells revealed the diploid number 2n = 18, with mostly metacentric chromosomes. Metaphase I cells exhibited 2n = 8II+Xyp and a parachute configuration of the sex chromosomes. Spermatogonial metaphase cells submitted to C-banding showed the presence of small dots of constitutive heterochromatin in the centromeric regions of nearly all the autosomes and on the short arm of the X chromosome (Xp, as well as an additional band on one of the arms of pair 1. Mitotic cells submitted to double staining with base-specific fluorochromes (DAPI-CMA3 revealed no regions rich in A+T or G+C sequences. Analysis of spermatogonial mitotic cells after sequential Giemsa/AgNO3 staining did not reveal any specific mark on the chromosomes. Meiotic metaphase I cells stained with silver nitrate revealed a strong impregnation associated to the sex chromosomes, and in situ hybridization with an 18S rDNA probe showed ribosomal cistrons in an autosomal bivalent.

  20. Karyotype, heterochromatin distribution and meiosis of Zabrotes subfasciatus (Bohemann) (Coleoptera: Chrysomelidae, Bruchinae)

    International Nuclear Information System (INIS)

    Correa, Ronan X.; Santos, Igor S.; Silva, Janisete G.; Costa, Marco A.; Pompolo, Silvia G.

    2008-01-01

    Zabrotes subfasciatus (Boh.) has been extensively studied in its agronomic and biochemical aspects due to its importance as a damaging insect to leguminous grains during storage. The few cytogenetic studies published on this species yielded conflicting results. In this study, the karyotype was analyzed in order to accurately describe the chromosome C-banding patterns and meiosis. The brain ganglion at the pre pupa and the adult and pupal testes were analyzed. All individuals had 26 chromosomes in both brain ganglion and spermatogonic mitotic metaphases. These chromosomes were classified as follows: the 12 th pair and the Y chromosome were telocentric; the X chromosome was acrocentric; the 4 th and 5 th pairs were sub metacentric; and the remaining pairs were all metacentric. One of the members of the 5 th pair presented a secondary constriction. All chromosomes presented pericentromeric heterochromatin. The large arms of the pairs 5, 9 and X presented heterochromatin. The X chromosome showed to be heteropyknotic throughout the prophase of the fi rst meiotic division. The sub phases of prophase I were atypical and meiosis II was rarely identified. Testes of all males showed a few cells; the bivalents were rod-like shaped in metaphase I. Karyological formulae were 2n = 24 + XX in females and 2n = 24 + XYp and either n = 12 + X or n = 12 + Y in males. (author)

  1. Karyotype, heterochromatin distribution and meiosis of Zabrotes subfasciatus (Bohemann) (Coleoptera: Chrysomelidae, Bruchinae)

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Ronan X.; Santos, Igor S.; Silva, Janisete G.; Costa, Marco A. [Universidade Estadual de Santa Cruz, Ilheus, BA (Brazil). Dept. de Ciencias Biologicas; Pompolo, Silvia G. [Universidade Federal de Vicosa, MG (Brazil). Dept. de Biologia Geral

    2008-09-15

    Zabrotes subfasciatus (Boh.) has been extensively studied in its agronomic and biochemical aspects due to its importance as a damaging insect to leguminous grains during storage. The few cytogenetic studies published on this species yielded conflicting results. In this study, the karyotype was analyzed in order to accurately describe the chromosome C-banding patterns and meiosis. The brain ganglion at the pre pupa and the adult and pupal testes were analyzed. All individuals had 26 chromosomes in both brain ganglion and spermatogonic mitotic metaphases. These chromosomes were classified as follows: the 12{sup th} pair and the Y chromosome were telocentric; the X chromosome was acrocentric; the 4{sup th} and 5{sup th} pairs were sub metacentric; and the remaining pairs were all metacentric. One of the members of the 5{sup th} pair presented a secondary constriction. All chromosomes presented pericentromeric heterochromatin. The large arms of the pairs 5, 9 and X presented heterochromatin. The X chromosome showed to be heteropyknotic throughout the prophase of the fi rst meiotic division. The sub phases of prophase I were atypical and meiosis II was rarely identified. Testes of all males showed a few cells; the bivalents were rod-like shaped in metaphase I. Karyological formulae were 2n = 24 + XX in females and 2n = 24 + XYp and either n = 12 + X or n = 12 + Y in males. (author)

  2. Heterochromatin and molecular characterization of DsmarMITE transposable element in the beetle Dichotomius schiffleri (Coleoptera: Scarabaeidae).

    Science.gov (United States)

    Xavier, Crislaine; Cabral-de-Mello, Diogo Cavalcanti; de Moura, Rita Cássia

    2014-12-01

    Cytogenetic studies of the Neotropical beetle genus Dichotomius (Scarabaeinae, Coleoptera) have shown dynamism for centromeric constitutive heterochromatin sequences. In the present work we studied the chromosomes and isolated repetitive sequences of Dichotomius schiffleri aiming to contribute to the understanding of coleopteran genome/chromosomal organization. Dichotomius schiffleri presented a conserved karyotype and heterochromatin distribution in comparison to other species of the genus with 2n = 18, biarmed chromosomes, and pericentromeric C-positive blocks. Similarly to heterochromatin distributional patterns, the highly and moderately repetitive DNA fraction (C 0 t-1 DNA) was detected in pericentromeric areas, contrasting with the euchromatic mapping of an isolated TE (named DsmarMITE). After structural analyses, the DsmarMITE was classified as a non-autonomous element of the type miniature inverted-repeat transposable element (MITE) with terminal inverted repeats similar to Mariner elements of insects from different orders. The euchromatic distribution for DsmarMITE indicates that it does not play a part in the dynamics of constitutive heterochromatin sequences.

  3. A spherical harmonics intensity model for 3D segmentation and 3D shape analysis of heterochromatin foci.

    Science.gov (United States)

    Eck, Simon; Wörz, Stefan; Müller-Ott, Katharina; Hahn, Matthias; Biesdorf, Andreas; Schotta, Gunnar; Rippe, Karsten; Rohr, Karl

    2016-08-01

    The genome is partitioned into regions of euchromatin and heterochromatin. The organization of heterochromatin is important for the regulation of cellular processes such as chromosome segregation and gene silencing, and their misregulation is linked to cancer and other diseases. We present a model-based approach for automatic 3D segmentation and 3D shape analysis of heterochromatin foci from 3D confocal light microscopy images. Our approach employs a novel 3D intensity model based on spherical harmonics, which analytically describes the shape and intensities of the foci. The model parameters are determined by fitting the model to the image intensities using least-squares minimization. To characterize the 3D shape of the foci, we exploit the computed spherical harmonics coefficients and determine a shape descriptor. We applied our approach to 3D synthetic image data as well as real 3D static and real 3D time-lapse microscopy images, and compared the performance with that of previous approaches. It turned out that our approach yields accurate 3D segmentation results and performs better than previous approaches. We also show that our approach can be used for quantifying 3D shape differences of heterochromatin foci. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. The expansion of heterochromatin blocks in rye reflects the co-amplification of tandem repeats and adjacent transposable elements

    Czech Academy of Sciences Publication Activity Database

    Evtushenko, E.V.; Levitsky, V.G.; Elisafenko, E.A.; Gunbin, K.V.; Belousov, A.I.; Šafář, Jan; Doležel, Jaroslav; Vershinin, A.V.

    2016-01-01

    Roč. 17, MAY 4 (2016), s. 337 ISSN 1471-2164 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Tandem repeats * Transposable elements * Subtelomeric heterochromatin Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.729, year: 2016

  5. Erasure of CpG methylation in Arabidopsis alters patterns of histone H3 methylation in heterochromatin

    DEFF Research Database (Denmark)

    Tariq, M.; Saze, H.; Probst, A.

    2003-01-01

    In mammals and plants, formation of heterochromatin is associated with hypermethylation of DNA at CpG sites and histone H3 methylation at lysine 9. Previous studies have revealed that maintenance of DNA methylation in Neurospora and Arabidopsis requires histone H3 methylation. A feedback loop from...

  6. Single-Column Model Simulations of Subtropical Marine Boundary-Layer Cloud Transitions Under Weakening Inversions: SCM SIMULATIONS OF CLOUD TRANSITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Neggers, R. A. J. [Institute for Geophysics and Meteorology, Department of Geosciences, University of Cologne, Cologne Germany; Royal Netherlands Meteorological Institute, De Bilt The Netherlands; Ackerman, A. S. [NASA Goddard Institute for Space Studies, New York NY USA; Angevine, W. M. [CIRES, University of Colorado, Boulder CO USA; NOAA Earth System Research Laboratory, Boulder CO USA; Bazile, E. [Météo France/CNRM, Toulouse France; Beau, I. [Météo France/ENM, Toulouse France; Blossey, P. N. [Department of Atmospheric Sciences, University of Washington, Seattle WA USA; Boutle, I. A. [Met Office, Exeter UK; de Bruijn, C. [Royal Netherlands Meteorological Institute, De Bilt The Netherlands; Cheng, A. [NOAA Center for Weather and Climate Prediction, Environmental Modeling Center, College Park MD USA; van der Dussen, J. [Department of Geoscience and Remote Sensing, Delft University of Technology, Delft The Netherlands; Fletcher, J. [Department of Atmospheric Sciences, University of Washington, Seattle WA USA; University of Leeds, Leeds UK; Dal Gesso, S. [Institute for Geophysics and Meteorology, Department of Geosciences, University of Cologne, Cologne Germany; Royal Netherlands Meteorological Institute, De Bilt The Netherlands; Jam, A. [Météo-France/CNRM & CNRS/IPSL/LMD, Toulouse France; Kawai, H. [Meteorological Research Institute, Climate Research Department, Japan Meteorological Agency, Tsukuba Japan; Cheedela, S. K. [Department of Atmosphere in the Earth System, Max-Planck Institut für Meteorologie, Hamburg Germany; Larson, V. E. [Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee WI USA; Lefebvre, M. -P. [Météo-France/CNRM & CNRS/IPSL/LMD, Toulouse France; Lock, A. P. [Met Office, Exeter UK; Meyer, N. R. [Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee WI USA; de Roode, S. R. [Department of Geoscience and Remote Sensing, Delft University of Technology, Delft The Netherlands; de Rooy, W. [Royal Netherlands Meteorological Institute, De Bilt The Netherlands; Sandu, I. [Section of Physical Aspects, European Centre for Medium-Range Weather Forecasts, Reading UK; Xiao, H. [University of California at Los Angeles, Los Angeles CA USA; Pacific Northwest National Laboratory, Richland WA USA; Xu, K. -M. [NASA Langley Research Centre, Hampton VI USA

    2017-10-01

    Results are presented of the GASS/EUCLIPSE single-column model inter-comparison study on the subtropical marine low-level cloud transition. A central goal is to establish the performance of state-of-the-art boundary-layer schemes for weather and climate mod- els for this cloud regime, using large-eddy simulations of the same scenes as a reference. A novelty is that the comparison covers four different cases instead of one, in order to broaden the covered parameter space. Three cases are situated in the North-Eastern Pa- cific, while one reflects conditions in the North-Eastern Atlantic. A set of variables is considered that reflects key aspects of the transition process, making use of simple met- rics to establish the model performance. Using this method some longstanding problems in low level cloud representation are identified. Considerable spread exists among models concerning the cloud amount, its vertical structure and the associated impact on radia- tive transfer. The sign and amplitude of these biases differ somewhat per case, depending on how far the transition has progressed. After cloud breakup the ensemble median ex- hibits the well-known “too few too bright” problem. The boundary layer deepening rate and its state of decoupling are both underestimated, while the representation of the thin capping cloud layer appears complicated by a lack of vertical resolution. Encouragingly, some models are successful in representing the full set of variables, in particular the verti- cal structure and diurnal cycle of the cloud layer in transition. An intriguing result is that the median of the model ensemble performs best, inspiring a new approach in subgrid pa- rameterization.

  7. Arabidopsis HDA6 regulates locus-directed heterochromatin silencing in cooperation with MET1.

    Directory of Open Access Journals (Sweden)

    Taiko Kim To

    2011-04-01

    Full Text Available Heterochromatin silencing is pivotal for genome stability in eukaryotes. In Arabidopsis, a plant-specific mechanism called RNA-directed DNA methylation (RdDM is involved in heterochromatin silencing. Histone deacetylase HDA6 has been identified as a component of such machineries; however, its endogenous targets and the silencing mechanisms have not been analyzed globally. In this study, we investigated the silencing mechanism mediated by HDA6. Genome-wide transcript profiling revealed that the loci silenced by HDA6 carried sequences corresponding to the RDR2-dependent 24-nt siRNAs, however their transcript levels were mostly unaffected in the rdr2 mutant. Strikingly, we observed significant overlap of genes silenced by HDA6 to those by the CG DNA methyltransferase MET1. Furthermore, regardless of dependence on RdDM pathway, HDA6 deficiency resulted in loss of heterochromatic epigenetic marks and aberrant enrichment for euchromatic marks at HDA6 direct targets, along with ectopic expression of these loci. Acetylation levels increased significantly in the hda6 mutant at all of the lysine residues in the H3 and H4 N-tails, except H4K16. Interestingly, we observed two different CG methylation statuses in the hda6 mutant. CG methylation was sustained in the hda6 mutant at some HDA6 target loci that were surrounded by flanking DNA-methylated regions. In contrast, complete loss of CG methylation occurred in the hda6 mutant at the HDA6 target loci that were isolated from flanking DNA methylation. Regardless of CG methylation status, CHG and CHH methylation were lost and transcriptional derepression occurred in the hda6 mutant. Furthermore, we show that HDA6 binds only to its target loci, not the flanking methylated DNA, indicating the profound target specificity of HDA6. We propose that HDA6 regulates locus-directed heterochromatin silencing in cooperation with MET1, possibly recruiting MET1 to specific loci, thus forming the foundation of silent

  8. Identification of the pattern of heterochromatin distribution in Passiflora species with C-banding.

    Science.gov (United States)

    Viana, A J C; Souza, M M

    2010-09-28

    We tested four C-banding protocols to obtain heterochromatic bands in the passion fruit species Passiflora edulis and P. cacaoensis (Passifloraceae). Three of these protocols had been previously described. The three published protocols were not adequate to obtain C-bands in these species. An adapted protocol demonstrated heterochromatin distribution in metaphasic chromosomes of species of Passiflora for the first time. The differentiated coloration for C-bands was obtained with immersion of the slides in 99% ethanol, 45% acetic acid (additional step), 0.2 N hydrochloric acid, hydroxide of barium, 45% acetic acid, and 2X standard saline citrate at four different temperatures. The C-bands were observed in the satellites and in the telomere and centromere regions of all chromosomes, both in P. edulis and in P. cacaoensis.

  9. Nuclear dynamics of radiation-induced foci in euchromatin and heterochromatin

    International Nuclear Information System (INIS)

    Chiolo, Irene; Tang, Jonathan; Georgescu, Walter; Costes, Sylvain V.

    2013-01-01

    Repair of double strand breaks (DSBs) is essential for cell survival and genome integrity. While much is known about the molecular mechanisms involved in DSB repair and checkpoint activation, the roles of nuclear dynamics of radiation-induced foci (RIF) in DNA repair are just beginning to emerge. Here, we summarize results from recent studies that point to distinct features of these dynamics in two different chromatin environments: heterochromatin and euchromatin. We also discuss how nuclear architecture and chromatin components might control these dynamics, and the need of novel quantification methods for a better description and interpretation of these phenomena. These studies are expected to provide new biomarkers for radiation risk and new strategies for cancer detection and treatment

  10. Nuclear dynamics of radiation-induced foci in euchromatin and heterochromatin

    Energy Technology Data Exchange (ETDEWEB)

    Chiolo, Irene; Tang, Jonathan; Georgescu, Walter; Costes, Sylvain V.

    2013-10-01

    Repair of double strand breaks (DSBs) is essential for cell survival and genome integrity. While much is known about the molecular mechanisms involved in DSB repair and checkpoint activation, the roles of nuclear dynamics of radiation-induced foci (RIF) in DNA repair are just beginning to emerge. Here, we summarize results from recent studies that point to distinct features of these dynamics in two different chromatin environments: heterochromatin and euchromatin. We also discuss how nuclear architecture and chromatin components might control these dynamics, and the need of novel quantification methods for a better description and interpretation of these phenomena. These studies are expected to provide new biomarkers for radiation risk and new strategies for cancer detection and treatment.

  11. Polymorphic organization of constitutive heterochromatin in Equus asinus (2n = 62) chromosome 1.

    Science.gov (United States)

    Raimondi, Elena; Piras, Francesca M; Nergadze, Solomon G; Di Meo, Giulia Pia; Ruiz-Herrera, Aurora; Ponsà, Montserrat; Ianuzzi, Leopoldo; Giulotto, Elena

    2011-06-01

    In the karyotype of Equus asinus (domestic donkey, 2n = 62), non-centromeric heterochromatic bands have been described in subcentromeric and telomeric positions. In particular, chromosome 1 is characterised by heterochromatic bands in the proximal region of the long arm and in the short arm; it has been shown that these regions are polymorphic in size. Here we investigated the variation in the intensity and distribution of fluorescence signals observed on donkey chromosome 1 after in situ hybridization with two DNA probes containing fragments from the two major equine satellite DNA families. Our results show that, in Equus asinus chromosome 1, the amount and distribution of large clusters of satellite DNA can define at least nine polymorphic variants of the constitutive heterochromatin that cannot be detected by C-banding alone. © 2011 The Authors.

  12. Histone epigenetic marks in heterochromatin and euchromatin of the Chagas' disease vector, Triatoma infestans.

    Science.gov (United States)

    Alvarenga, Elenice M; Rodrigues, Vera L C C; Moraes, Alberto S; Naves, Luisa S; Mondin, Mateus; Felisbino, Marina B; Mello, Maria Luiza S

    2016-05-01

    Triatoma infestans, a vector of Chagas' disease, shows several particular cell biology characteristics, including the presence of conspicuous heterochromatic bodies (chromocenters) where DNA methylation has not been previously detected. Whether histone modifications contribute to the condensed state of these bodies has not yet been studied. Here, we investigated epigenetic modifications of histones H3 and H4 and presence of the non-histone heterochromatin protein (HP1-α) in the chromocenters and euchromatin of T. infestans cell nuclei, using immunocytochemistry. The effect of different concentrations of the histone deacetylase inhibitors valproic acid (VPA) and sodium butyrate (NaBt) on chromocenter condensation was visually examined; in VPA-treated specimens, this effect was also analyzed by image analysis. Trimethylated H3K9 signals, which were revealed in chromocenter and non-chromocenter areas, were strongest in chromocenters, whereas selected acetylated histone marks and mono- and dimethylated H3K9 and H4K20 signals were detected only in euchromatin. Weak trimethylated H4K20 signals and variable distribution of HP1-α were detected in chromocenters of part of the cellular population analyzed. Although specific VPA and NaBt treatment conditions affected the heterochromatin condensation pattern, they did not induce a decrease in survival and molting rates of the T. infestans nymphs. The VPA-induced chromatin remodeling was not accompanied by induction of H3K9 acetylation in chromocenters. Present findings regarding histone modifications and effects following VPA or NaBt treatments did not yet solve the question of which factors are responsible for maintenance of the condensed state of chromocenters in T. infestans. A possibility requiring further investigation remains on histone methylation marks and/or non-histone proteins. Copyright © 2016 Elsevier GmbH. All rights reserved.

  13. Threshold voltage variation depending on single grain boundary and stored charges in an adjacent cell for vertical silicon–oxide–nitride–oxide–silicon NAND flash memory

    Science.gov (United States)

    Oh, Hyeongwan; Kim, Jiwon; Baek, Rock-Hyun; Lee, Jeong-Soo

    2018-04-01

    The effects of single grain boundary (SGB) position and stored electron charges in an adjacent cell in silicon–oxide–nitride–oxide–silicon (SONOS) structures on the variations of threshold voltage (V th) were investigated using technology computer-aided design (TCAD) simulation. As the bit line voltage increases, the SGB position causing the maximum V th variation was shifted from the center to the source side in the channel, owing to the drain-induced grain barrier lowering effect. When the SGB is located in the spacer region, the potential interaction from both the SGB and the stored electron charges in the adjacent cell becomes significant and thus resulting in larger V th variation. In contrast, when the SGB is located at the center of the channel, the peak position of potential barrier is shifted to the center, so that the influence of the adjacent cell is diminished. As the gate length is scaled down to 20 nm, the influence of stored charges in adjacent cells becomes significant, resulting in larger V th variations.

  14. High-affinity binding of Chp1 chromodomain to K9 methylated histone H3 is required to establish centromeric heterochromatin.

    Science.gov (United States)

    Schalch, Thomas; Job, Godwin; Noffsinger, Victoria J; Shanker, Sreenath; Kuscu, Canan; Joshua-Tor, Leemor; Partridge, Janet F

    2009-04-10

    In fission yeast, assembly of centromeric heterochromatin requires the RITS complex, which consists of Ago1, Tas3, Chp1, and siRNAs derived from centromeric repeats. Recruitment of RITS to centromeres has been proposed to depend on siRNA-dependent targeting of Ago1 to centromeric sequences. Previously, we demonstrated that methylated lysine 9 of histone H3 (H3K9me) acts upstream of siRNAs during heterochromatin establishment. Our crystal structure of Chp1's chromodomain in complex with a trimethylated lysine 9 H3 peptide reveals extensive sites of contact that contribute to Chp1's high-affinity binding. We found that this high-affinity binding is critical for the efficient establishment of centromeric heterochromatin, but preassembled heterochromatin can be maintained when Chp1's affinity for H3K9me is greatly reduced.

  15. Variation of the interphase heterochromatin in Artemia (Crustacea, Anostraca) of the Americas is related to changes in nuclear size and ionic composition of hipersaline habitats

    OpenAIRE

    Parraguez, M.; Gajardo, G.

    2017-01-01

    Abstract The populations of Artemia (or brine shrimp) from the Americas exhibit a wide variation in the amount of interphase heterochromatin. There is interest in understanding how this variation affects different parameters, from the cellular to the organismal levels. This should help to clarify the ability of this organism to tolerate brine habitats regularly subject to strong abiotic changes. In this study, we assessed the amount of interphase heterochromatin per nucleus based on chromocen...

  16. Single-Particle Measurements of Midlatitude Black Carbon and Light-Scattering Aerosols from the Boundary Layer to the Lower Stratosphere

    Science.gov (United States)

    Schwartz, J. P.; Gao, R. S.; Fahey, D. W.; Thomson, D. S.; Watts, L. A.; Wilson, J. C.; Reeves, J. M.; Darbeheshti, M.; Baumgardner, D. G.; Kok, G. L.; hide

    2006-01-01

    A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, Texas. The SP2 uses laser-induced incandescence to detect individual black carbon (BC) particles in an air sample in the mass range of approx.3-300 fg (approx.0.15-0.7 microns volume equivalent diameter). Scattered light is used to size the remaining non-BC aerosols in the range of approx.0.17-0.7 microns diameter. We present profiles of both aerosol types from the boundary layer to the lower stratosphere from two midlatitude flights. Results for total aerosol amounts in the size range detected by the SP2 are in good agreement with typical particle spectrometer measurements in the same region. All ambient incandescing particles were identified as BC because their incandescence properties matched those of laboratory-generated BC aerosol. Approximately 40% of these BC particles showed evidence of internal mixing (e.g., coating). Throughout profiles between 5 and 18.7 km, BC particles were less than a few percent of total aerosol number, and black carbon aerosol (BCA) mass mixing ratio showed a constant gradient with altitude above 5 km. SP2 data was compared to results from the ECHAM4/MADE and LmDzT-INCA global aerosol models. The comparison will help resolve the important systematic differences in model aerosol processes that determine BCA loadings. Further intercomparisons of models and measurements as presented here will improve the accuracy of the radiative forcing contribution from BCA.

  17. Chromosome study in Schistocerca (Orthoptera-Acrididae-Cyrtacanthacridinae: karyotypes and distribution patterns of constitutive heterochromatin and nucleolus organizer regions (NORs

    Directory of Open Access Journals (Sweden)

    Maria José de Souza

    2007-01-01

    Full Text Available Chromosome analyses were performed in two grasshopper species of the genus Schistocerca, S. pallens and S. flavofasciata. Both species shared the same diploid number (2n = 23, X in males; 2n = 24, XX in females;and a conserved karyotype composed exclusively of acrocentric chromosomes, but differed in their distribution patterns of constitutive heterochromatin and nucleolus organizer regions (NORs. Constitutive heterochromatin was located in the pericentromeric region of all chromosomes in both species. S. flavofasciata presented an additional C-band on the distal region of the long arm of a small autosome pair (S9. Nucleolus organizer regions (NORs, revealed by silver nitrate staining (Ag-NORs, were observed on a medium autosome pair (M5 in both species. S. pallens presented an additional NOR-bearing autosome (M6. The same sites were labeled after FISH with an rDNA probe in S. pallens cells.

  18. Herpesviral ICP0 Protein Promotes Two Waves of Heterochromatin Removal on an Early Viral Promoter during Lytic Infection

    Directory of Open Access Journals (Sweden)

    Jennifer S. Lee

    2016-01-01

    Full Text Available Herpesviruses must contend with host cell epigenetic silencing responses acting on their genomes upon entry into the host cell nucleus. In this study, we confirmed that unchromatinized herpes simplex virus 1 (HSV-1 genomes enter primary human foreskin fibroblasts and are rapidly subjected to assembly of nucleosomes and association with repressive heterochromatin modifications such as histone 3 (H3 lysine 9-trimethylation (H3K9me3 and lysine 27-trimethylation (H3K27me3 during the first 1 to 2 h postinfection. Kinetic analysis of the modulation of nucleosomes and heterochromatin modifications over the course of lytic infection demonstrates a progressive removal that coincided with initiation of viral gene expression. We obtained evidence for three phases of heterochromatin removal from an early gene promoter: an initial removal of histones and heterochromatin not dependent on ICP0, a second ICP0-dependent round of removal of H3K9me3 that is independent of viral DNA synthesis, and a third phase of H3K27me3 removal that is dependent on ICP0 and viral DNA synthesis. The presence of ICP0 in transfected cells is also sufficient to promote removal of histones and H3K9me3 modifications of cotransfected genes. Overall, these results show that ICP0 promotes histone removal, a reduction of H3K9me3 modifications, and a later indirect reduction of H3K27me3 modifications following viral early gene expression and DNA synthesis. Therefore, HSV ICP0 promotes the reversal of host epigenetic silencing mechanisms by several mechanisms.

  19. Karyotype characterization and evolution in South American species of Lathyrus (Notolathyrus, Leguminosae) evidenced by heterochromatin and rDNA mapping.

    Science.gov (United States)

    Chalup, Laura; Samoluk, Sergio Sebastián; Neffa, Viviana Solís; Seijo, Guillermo

    2015-11-01

    Notolathyrus is a section of South American endemic species of the genus Lathyrus. The origin, phylogenetic relationship and delimitation of some species are still controversial. The present study provides an exhaustive analysis of the karyotypes of approximately half (10) of the species recognized for section Notolathyrus and four outgroups (sections Lathyrus and Orobus) by cytogenetic mapping of heterochromatic bands and 45S and 5S rDNA loci. The bulk of the parameters analyzed here generated markers to identify most of the chromosomes in the complements of the analyzed species. Chromosome banding showed interspecific variation in the amount and distribution of heterochromatin, and together with the distribution of rDNA loci, allowed the characterization of all the species studied here. Additionally, some of the chromosome parameters described (st chromosomes and the 45S rDNA loci) constitute the first diagnostic characters for the Notolathyrus section. Evolutionary, chromosome data revealed that the South American species are a homogeneous group supporting the monophyly of the section. Variation in the amount of heterochromatin was not directly related to the variation in DNA content of the Notolathyrus species. However, the correlation observed between the amount of heterochromatin and some geographical and bioclimatic variables suggest that the variation in the heterochromatic fraction should have an adaptive value.

  20. Negotiating boundaries

    DEFF Research Database (Denmark)

    Aarhus, Rikke; Ballegaard, Stinne Aaløkke

    2010-01-01

    to maintain the order of the home when managing disease and adopting new healthcare technology. In our analysis we relate this boundary work to two continuums of visibility-invisibility and integration-segmentation in disease management. We explore five factors that affect the boundary work: objects......To move treatment successfully from the hospital to that of technology assisted self-care at home, it is vital in the design of such technologies to understand the setting in which the health IT should be used. Based on qualitative studies we find that people engage in elaborate boundary work......, activities, places, character of disease, and collaboration. Furthermore, the processes are explored of how boundary objects move between social worlds pushing and shaping boundaries. From this we discuss design implications for future healthcare technologies for the home....

  1. Boundary Spanning

    DEFF Research Database (Denmark)

    Zølner, Mette

    The paper explores how locals span boundaries between corporate and local levels. The aim is to better comprehend potentialities and challenges when MNCs draws on locals’ culture specific knowledge. The study is based on an in-depth, interpretive case study of boundary spanning by local actors...... in the period of post-acquisition when their organization is being integrated into the acquiring MNC. The paper contributes to the literature on boundary spanning in three ways: First, by illustrating that boundary spanning is performed by numerous organizational actors in a variety of positions in MNCs......, inclusively by locals in subsidiaries. Second, by showing that boundary spanning is ‘situated’ in the sense that its result depends on the kind of knowledge to be transmitted and the attitude of the receivers. A third contribution is methodological. The study illustrates that combining bottom-up grounded...

  2. Comparative Chromosome Map and Heterochromatin Features of the Gray Whale Karyotype (Cetacea).

    Science.gov (United States)

    Kulemzina, Anastasia I; Proskuryakova, Anastasia A; Beklemisheva, Violetta R; Lemskaya, Natalia A; Perelman, Polina L; Graphodatsky, Alexander S

    2016-01-01

    Cetacean karyotypes possess exceptionally stable diploid numbers and highly conserved chromosomes. To date, only toothed whales (Odontoceti) have been analyzed by comparative chromosome painting. Here, we studied the karyotype of a representative of baleen whales, the gray whale (Eschrichtius robustus, Mysticeti), by Zoo-FISH with dromedary camel and human chromosome-specific probes. We confirmed a high degree of karyotype conservation and found an identical order of syntenic segments in both branches of cetaceans. Yet, whale chromosomes harbor variable heterochromatic regions constituting up to a third of the genome due to the presence of several types of repeats. To investigate the cause of this variability, several classes of repeated DNA sequences were mapped onto chromosomes of whale species from both Mysticeti and Odontoceti. We uncovered extensive intrapopulation variability in the size of heterochromatic blocks present in homologous chromosomes among 3 individuals of the gray whale by 2-step differential chromosome staining. We show that some of the heteromorphisms observed in the gray whale karyotype are due to distinct amplification of a complex of common cetacean repeat and heavy satellite repeat on homologous autosomes. Furthermore, we demonstrate localization of the telomeric repeat in the heterochromatin of both gray and pilot whale (Globicephala melas, Odontoceti). Heterochromatic blocks in the pilot whale represent a composite of telomeric and common repeats, while heavy satellite repeat is lacking in the toothed whale consistent with previous studies. © 2016 S. Karger AG, Basel.

  3. VIM1, a methylcytosine-binding protein required for centromeric heterochromatinization

    Science.gov (United States)

    Woo, Hye Ryun; Pontes, Olga; Pikaard, Craig S.; Richards, Eric J.

    2007-01-01

    Epigenetic regulation in eukaryotes is executed by a complex set of signaling interactions among small RNA species and chromatin marks, including histone modification and DNA methylation. We identified vim1 (VARIANT IN METHYLATION 1), an Arabidopsis mutation causing cytosine hypomethylation and decondensation of centromeres in interphase. VIM1 is a member of a small gene family, encoding proteins containing PHD, RING, and SRA (SET- and RING-associated) domains, which are found together in mammalian proteins implicated in regulation of chromatin modification, transcription, and the cell cycle. VIM1 is an unconventional methylcytosine-binding protein that interacts in vitro with 5mCpG- and 5mCpHpG-modified DNA (via its SRA domain), as well as recombinant histones (H2B, H3, H4, and HTR12) in plant extracts. VIM1 associates with methylated genomic loci in vivo and is enriched in chromocenters. Our findings suggest that VIM1 acts at the DNA methylation–histone interface to maintain centromeric heterochromatin. PMID:17242155

  4. Heterochromatin-Mediated Gene Silencing Facilitates the Diversification of Olfactory Neurons

    Directory of Open Access Journals (Sweden)

    David B. Lyons

    2014-11-01

    Full Text Available An astounding property of the nervous system is its cellular diversity. This diversity, which was initially realized by morphological and electrophysiological differences, is ultimately produced by variations in gene-expression programs. In most cases, these variations are determined by external cues. However, a growing number of neuronal types have been identified in which inductive signals cannot explain the few but decisive transcriptional differences that cause cell diversification. Here, we show that heterochromatic silencing, which we find is governed by histone methyltransferases G9a (KMT1C and GLP (KMT1D, is essential for stochastic and singular olfactory receptor (OR expression. Deletion of G9a and GLP dramatically reduces the complexity of the OR transcriptome, resulting in transcriptional domination by a few ORs and loss of singularity in OR expression. Thus, our data suggest that, in addition to its previously known functions, heterochromatin creates an epigenetic platform that affords stochastic, mutually exclusive gene choices and promotes cellular diversity.

  5. Boundary Spanning

    DEFF Research Database (Denmark)

    Zølner, Mette

    The paper explores how locals span boundaries between corporate and local levels. The aim is to better comprehend potentialities and challenges when MNCs draws on locals’ culture specific knowledge. The study is based on an in-depth, interpretive case study of boundary spanning by local actors in...... approach with pattern matching is a way to shed light on the tacit local knowledge that organizational actors cannot articulate and that an exclusively inductive research is not likely to unveil....

  6. HP1 recruits activity-dependent neuroprotective protein to H3K9me3 marked pericentromeric heterochromatin for silencing of major satellite repeats.

    Directory of Open Access Journals (Sweden)

    Kerstin Mosch

    Full Text Available H3 lysine 9 trimethylation (H3K9me3 is a histone posttranslational modification (PTM that has emerged as hallmark of pericentromeric heterochromatin. This constitutive chromatin domain is composed of repetitive DNA elements, whose transcription is differentially regulated. Mammalian cells contain three HP1 proteins, HP1α, HP1β and HP1γ These have been shown to bind to H3K9me3 and are thought to mediate the effects of this histone PTM. However, the mechanisms of HP1 chromatin regulation and the exact functional role at pericentromeric heterochromatin are still unclear. Here, we identify activity-dependent neuroprotective protein (ADNP as an H3K9me3 associated factor. We show that ADNP does not bind H3K9me3 directly, but that interaction is mediated by all three HP1 isoforms in vitro. However, in cells ADNP localization to areas of pericentromeric heterochromatin is only dependent on HP1α and HP1β. Besides a PGVLL sequence patch we uncovered an ARKS motif within the ADNP homeodomain involved in HP1 dependent H3K9me3 association and localization to pericentromeric heterochromatin. While knockdown of ADNP had no effect on HP1 distribution and heterochromatic histone and DNA modifications, we found ADNP silencing major satellite repeats. Our results identify a novel factor in the translation of H3K9me3 at pericentromeric heterochromatin that regulates transcription.

  7. Blurring Boundaries

    DEFF Research Database (Denmark)

    Neergaard, Ulla; Nielsen, Ruth

    2010-01-01

    of welfare functions into EU law both from an internal market law and a constitutional law perspective. The main problem areas covered by the Blurring Boundaries project were studied in sub-projects on: 1) Internal market law and welfare services; 2) Fundamental rights and non-discrimination law aspects......; and 3) Services of general interest. In the Blurring Boundaries project, three aspects of the European Social Model have been particularly highlighted: the constitutionalisation of the European Social Model, its multi-level legal character, and the clash between market access justice at EU level...... and distributive justice at national level....

  8. H3K9me-independent gene silencing in fission yeast heterochromatin by Clr5 and histone deacetylases

    DEFF Research Database (Denmark)

    Hansen, Klavs R; Hazan, Idit; Shanker, Sreenath

    2011-01-01

    . The genomic targets of Clr5 also include Ste11, a master regulator of sexual differentiation. Hence Clr5, like the multi-functional Atf1 transcription factor which also modulates chromatin structure in the mating-type region, controls sexual differentiation and genome integrity at several levels. Globally......, our results point to histone deacetylases as prominent repressors of gene expression in fission yeast heterochromatin. These deacetylases can act in concert with, or independently of, the widely studied H3K9me mark to influence gene silencing at heterochromatic loci....

  9. Monoallele deletion of CBP leads to pericentromeric heterochromatin condensation through ESET expression and histone H3 (K9) methylation.

    Science.gov (United States)

    Lee, Junghee; Hagerty, Sean; Cormier, Kerry A; Kim, Jinho; Kung, Andrew L; Ferrante, Robert J; Ryu, Hoon

    2008-06-15

    Chromatin remodeling is tightly controlled under physiological conditions. Alterations in chromatin structure are involved in the pathogenesis of neuronal systems. We found that the monoallelic deletion of CREB binding protein (CBP) results in the induction of ERG-associated protein with SET domain (ESET) and increases trimethylation of histone H3 (K9) and condensation of pericentromeric heterochromatin structure in neurons. Nested deletion and mutational analysis of the ESET promoter further demonstrated that the Ets-2 transcription factor regulates transcriptional activity of the ESET gene. In CBP+/- mice, Ets-2 occupancy in the ESET promoter DNA was markedly elevated. Our results suggest that CBP is a transcriptional repressor of ESET gene expression by limiting Ets-2 transcriptional activity, while CBP siRNA enhances basal and Ets-2-dependent ESET transcriptional activity. Altered expression of the ESET gene and hypertrimethylation of H3 (K9) correlate with striatal neuron atrophy and dysfunction in CBP+/- mice. These results establish an alternative pathway that loss of CBP leads to the pericentric heterochromatin condensation through ESET expression and trimethylation of H3 (K9).

  10. Male and female meiosis in the mountain scorpion Zabius fuscus (Scorpiones, Buthidae): heterochromatin, rDNA and TTAGG telomeric repeats.

    Science.gov (United States)

    Adilardi, Renzo Sebastián; Ojanguren-Affilastro, Andrés Alejandro; Mattoni, Camilo Iván; Mola, Liliana María

    2015-08-01

    All cytogenetically studied scorpions present male achiasmatic meiosis and lack heteromorphic sex chromosomes. In contrast, information about female meiosis in scorpions is scarce due to the difficulty of finding meiotic cells. The genus Zabius includes three described species and no chromosome studies have been performed on it until now. We analyzed the constitutive heterochromatin distribution, NORs and telomeric sequences in mitosis and meiosis of males and females of different populations of Zabius fuscus. All specimens presented 2n = 18 holokinetic chromosomes that gradually decreased in size. Male meiosis presented nine bivalents and a polymorphism for one reciprocal translocation in one population. Telomeric signals were detected at every terminal region, confirming also the presence of a (TTAGG) n motif in Buthidae. Constitutive heterochromatin was found in three chromosome pairs at a terminal region; moreover, NORs were embedded in the heterochromatic region of the largest pair. Chromosome size and landmarks allowed us to propose the chromosomes involved in the rearrangement. In four females, cells at different prophase I stages were analyzed. We describe a diffuse stage and the presence of ring-shaped bivalents. We discuss the possible origin of these bivalents in the framework of chiasmatic or achiasmatic female meiosis. These results contribute to increase the scarce evidence of female meiosis in scorpions and raise new questions about its mechanism.

  11. Age-Associated Decrease of the Histone Methyltransferase SUV39H1 in HSC Perturbs Heterochromatin and B Lymphoid Differentiation

    Directory of Open Access Journals (Sweden)

    Dounia Djeghloul

    2016-06-01

    Full Text Available The capacity of hematopoietic stem cells (HSC to generate B lymphocytes declines with age, contributing to impaired immune function in the elderly. Here we show that the histone methyltransferase SUV39H1 plays an important role in human B lymphoid differentiation and that expression of SUV39H1 decreases with age in both human and mouse HSC, leading to a global reduction in H3K9 trimethylation and perturbed heterochromatin function. Further, we demonstrate that SUV39H1 is a target of microRNA miR-125b, a known regulator of HSC function, and that expression of miR-125b increases with age in human HSC. Overexpression of miR-125b and inhibition of SUV39H1 in young HSC induced loss of B cell potential. Conversely, both inhibition of miR-125 and enforced expression of SUV39H1 improved the capacity of HSC from elderly individuals to generate B cells. Our findings highlight the importance of heterochromatin regulation in HSC aging and B lymphopoiesis.

  12. Boundary Migration in Rutile

    Energy Technology Data Exchange (ETDEWEB)

    Gilliss, S.R.; Ravishankar, N.; Farrer, J.K.; Carter, C.B.

    2003-08-01

    TiO{sub 2} is a vital material in several technologies including, photocatalysis, gas sensing, biomaterials and optical coatings. Among the several crystal structures of this oxide, rutile has the highest density and microhardness, the highest index of refraction and the highest temperature stability. The processing of dense polycrystalline materials often includes the addition of a liquid-forming phase at higher temperatures. This technique is known as liquid-phase sintering and has been studied extensively. Rutile boundaries containing an amorphous phase have been used to study boundary migration and grain-boundary grooving. Visible-light (VLM), scanning electron (SEM) and transmission electron microscopy (TEM) in addition to electron-backscatter diffraction (EBSD) and a focused-ion beam (FIB) tool were used to characterize boundary migration in rutile. EBSD analysis was carried out on a Philips XL30 FEG SEM equipped with a DigiView 1612 high-resolution, high-speed CCD camera. A 2.5 cm sample-to-camera distance was used and {approx}70{sup o} sample tilt. A Philips CM30 operated at 300 kV was used for TEM characterization and an FEI DB235 was used for FIB work. Pulsed-laser deposition (PLD) has been used to deposit thin films ({approx}100 nm thick) of silica glass on single-crystals of rutile. The film/substrate assembly is then fabricated into bicrystals of known boundary-plane orientation by hot pressing. Bicrystals were fabricated with boundary planes of nominal surface orientation of (001) and (110). After diffusion bonding a surface perpendicular to the interface is cut and polished. Bicrystals are then heat treated in air at 1650 C for varying lengths of time. Figure 1 is a VLM image of a rutile bicrystal which as been heat treated for 4 hours. During this heat treatment migration of the boundary initiates at parallel grooves contained in the crystal on the right-hand side. EBSD analysis shows that this parallel set of grooves is due to the presence of 3{sup

  13. Repeat Composition of CenH3-chromatin and H3K9me2-marked heterochromatin in Sugar Beet (Beta vulgaris)

    Czech Academy of Sciences Publication Activity Database

    Kowar, T.; Zakrzewski, F.; Macas, Jiří; Koblížková, Andrea; Viehoever, P.; Weisshaar, B.; Schmidt, T.

    2016-01-01

    Roč. 16, č. 120 (2016) ISSN 1471-2229 R&D Projects: GA ČR GBP501/12/G090 Institutional support: RVO:60077344 Keywords : Centromere * CenH3 * H3K9me2 * Heterochromatin Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.964, year: 2016

  14. Bleeding boundaries

    DEFF Research Database (Denmark)

    Jørgensen, Kristian Møller; Petersen, Michael Nebeling

    2018-01-01

    Hook-up apps such as Grindr and Scruff have become important sites for the negotiation of sex between men, in that they shape the ways intimacy cultures are practised and become visible (Mowlabocus, 2010; Race, 2014; Duguay et al., 2016). While such apps enable different intimacy cultures......, they also come paired with anxieties. In the epigraph the interview participant James1 expresses concerns about the how the hook-up app Scruff might restructure the boundaries of privacy and make him vulnerable to exposure. Such technological ambivalence is central to domestication theory, which focuses...

  15. Breaking Boundaries

    DEFF Research Database (Denmark)

    . As a fundamental human experience, liminality transmits cultural practices, codes, rituals, and meanings in-between aggregate structures and uncertain outcomes. As a methodological tool it is well placed to overcome disciplinary boundaries, which often direct attention to specific structures or sectors of society....... Its capacity to provide explanatory accounts of seemingly unstructured situations provides an opportunity to link experience-based and culture-oriented approaches not only to contemporary problems but also to undertake comparisons across historical periods. From a perspective of liminality...

  16. Boundary issues

    Science.gov (United States)

    Townsend, Alan R.; Porder, Stephen

    2011-03-01

    What is our point of no return? Caesar proclaimed 'the die is cast' while crossing the Rubicon, but rarely does modern society find so visible a threshold in our continued degradation of ecosystems and the services they provide. Humans have always used their surroundings to make a living— sometimes successfully, sometimes not (Diamond 2005)—and we intuitively know that there are boundaries to our exploitation. But defining these boundaries has been a challenge since Malthus first prophesied that nature would limit the human population (Malthus 1798). In 2009, Rockström and colleagues tried to quantify what the 6.8 billion (and counting) of us could continue to get away with, and what we couldn't (Rockström et al 2009). In selecting ten 'planetary boundaries', the authors contend that a sustainable human enterprise requires treating a number of environmental thresholds as points of no return. They suggest we breach these Rubicons at our own peril, and that we've already crossed three: biodiversity loss, atmospheric CO2, and disruption of the global nitrogen (N) cycle. As they clearly hoped, the very act of setting targets has provoked scientific inquiry about their accuracy, and about the value of hard targets in the first place (Schlesinger 2009). Such debate is a good thing. Despite recent emphasis on the science of human-ecosystem interactions, understanding of our planetary boundaries is still in its infancy, and controversy can speed scientific progress (Engelhardt and Caplan 1987). A few weeks ago in this journal, Carpenter and Bennett (2011) took aim at one of the more controversial boundaries in the Rockström analysis: that for human alteration of the global phosphorus (P) cycle. Rockström's group chose riverine P export as the key indicator, suggesting that humans should not exceed a value that could trigger widespread marine anoxic events—and asserting that we have not yet crossed this threshold. There are defensible reasons for a marine

  17. Loss of heterochromatin protein 1 gamma reduces the number of primordial germ cells via impaired cell cycle progression in mice.

    Science.gov (United States)

    Abe, Kanae; Naruse, Chie; Kato, Tomoaki; Nishiuchi, Takumi; Saitou, Mitinori; Asano, Masahide

    2011-11-01

    Signals from extraembryonic tissues in mice determine which proximal epiblast cells become primordial germ cells (PGCs). After their specification, approximately 40 PGCs appear at the base of the allantoic bud and migrate to the genital ridges, where they expand to about 25 000 cells by Embryonic Day (E)13.5. The heterochromatin protein 1 (HP1) family members HP1alpha, HP1beta, and HP1gamma (CBX5, CBX1, and CBX3, respectively) are thought to induce heterochromatin structure and to regulate gene expression by binding methylated histone H3 lysine 9. We found a dramatic loss of germ cells before meiosis in HP1gamma mutant (HP1gamma(-/-)) mice that we generated previously. The reduction in PGCs in HP1gamma(-/-) embryos was detectable from the early bud stage (E7.25), and the number of HP1gamma(-/-) PGCs was gradually reduced thereafter. Bromodeoxyuridine incorporation into PGCs was significantly reduced in E7.25 and E12.5 HP1gamma(-/-) embryos. Furthermore, a lower proportion of HP1gamma(-/-) PGCs than wild-type PGCs was in S phase, and a higher proportion, respectively, was in G1 phase at E12.5. Moreover, the proportion of p21 (Cip, official symbol CDKN1A)-positive HP1gamma(-/-) PGCs was increased, suggesting that the G1/S phase transition was inhibited. However, no differences were detected between fate determination, migration, apoptosis, or histone modification of PGCs of control embryos and those of HP1gamma(-/-) embryos. Therefore, the reduction in PGCs in HP1gamma(-/-) embryos could be caused by impaired cell cycle in PGCs. These results suggest that HP1gamma plays an important role in keeping enough germ cells by regulating the PGC cell cycle.

  18. Euchromatin islands in large heterochromatin domains are enriched for CTCF binding and differentially DNA-methylated regions

    Directory of Open Access Journals (Sweden)

    Wen Bo

    2012-10-01

    Full Text Available Abstract Background The organization of higher order chromatin is an emerging epigenetic mechanism for understanding development and disease. We and others have previously observed dynamic changes during differentiation and oncogenesis in large heterochromatin domains such as Large Organized Chromatin K (lysine modifications (LOCKs, of histone H3 lysine-9 dimethylation (H3K9me2 or other repressive histone posttranslational modifications. The microstructure of these regions has not previously been explored. Results We analyzed the genome-wide distribution of H3K9me2 in two human pluripotent stem cell lines and three differentiated cells lines. We identified > 2,500 small regions with very low H3K9me2 signals in the body of LOCKs, which were termed as euchromatin islands (EIs. EIs are 6.5-fold enriched for DNase I Hypersensitive Sites and 8-fold enriched for the binding of CTCF, the major organizer of higher-order chromatin. Furthermore, EIs are 2–6 fold enriched for differentially DNA-methylated regions associated with tissue types (T-DMRs, reprogramming (R-DMRs and cancer (C-DMRs. Gene ontology (GO analysis suggests that EI-associated genes are functionally related to organ system development, cell adhesion and cell differentiation. Conclusions We identify the existence of EIs as a finer layer of epigenomic architecture within large heterochromatin domains. Their enrichment for CTCF sites and DNAse hypersensitive sites, as well as association with DMRs, suggest that EIs play an important role in normal epigenomic architecture and its disruption in disease.

  19. Senescent mouse cells fail to overtly regulate the HIRA histone chaperone and do not form robust Senescence Associated Heterochromatin Foci

    Directory of Open Access Journals (Sweden)

    Enders Greg H

    2010-06-01

    Full Text Available Abstract Background Cellular senescence is a permanent growth arrest that occurs in response to cellular stressors, such as telomere shortening or activation of oncogenes. Although the process of senescence growth arrest is somewhat conserved between mouse and human cells, there are some critical differences in the molecular pathways of senescence between these two species. Recent studies in human fibroblasts have defined a cell signaling pathway that is initiated by repression of a specific Wnt ligand, Wnt2. This, in turn, activates a histone chaperone HIRA, and culminates in formation of specialized punctate domains of facultative heterochromatin, called Senescence-Associated Heterochromatin Foci (SAHF, that are enriched in the histone variant, macroH2A. SAHF are thought to repress expression of proliferation-promoting genes, thereby contributing to senescence-associated proliferation arrest. We asked whether this Wnt2-HIRA-SAHF pathway is conserved in mouse fibroblasts. Results We show that mouse embryo fibroblasts (MEFs and mouse skin fibroblasts, do not form robust punctate SAHF in response to an activated Ras oncogene or shortened telomeres. However, senescent MEFs do exhibit elevated levels of macroH2A staining throughout the nucleus as a whole. Consistent with their failure to fully activate the SAHF assembly pathway, the Wnt2-HIRA signaling axis is not overtly regulated between proliferating and senescent mouse cells. Conclusions In addition to the previously defined differences between mouse and human cells in the mechanisms and phenotypes associated with senescence, we conclude that senescent mouse and human fibroblasts also differ at the level of chromatin and the signaling pathways used to regulate chromatin. These differences between human and mouse senescence may contribute to the increased propensity of mouse fibroblasts (and perhaps other mouse cell types to become immortalized and transformed, compared to human cells.

  20. Male meiosis, heterochromatin characterization and chromosomal location of rDNA in Microtomus lunifer (Berg, 1900 (Hemiptera: Reduviidae: Hammacerinae

    Directory of Open Access Journals (Sweden)

    María Poggio

    2011-05-01

    Full Text Available In the present work, we analysed the male meiosis, the content and distribution of heterochromatin and the number and location of nucleolus organizing regions in Microtomus lunifer (Berg, 1900 by means of standard technique, C- and fluorescent bandings, and fluorescent in situ hybridization with an 18S rDNA probe. This species is the second one cytogenetically analysed within the Hammacerinae. Its male diploid chromosome number is 31 (2n=28+X1X2Y, including a minute pair of m-chromosomes. The diploid autosomal number and the presence of m-chromosomes are similar to those reported in M. conspicillaris (Drury, 1782 (2n=28+XY. However, M. lunifer has a multiple sex chromosome system X1X2Y (male that could have originated by fragmentation of the ancestral X chromosome. Taking into account that M. conspicillaris and M. lunifer are the only two species within Reduviidae that possess m-chromosomes, the presence of this pair could be a synapomorphy for the species of this genus. C- and fluorescent bandings showed that the amount of heterochromatin in M. lunifer was small, and only a small CMA3 bright band was observed in the largest autosomal pair at one terminal region. FISH with the 18S rDNA probe demonstrated that ribosomal genes were terminally placed on the largest autosomal pair. Our present results led us to propose that the location of rDNA genes could be associated with variants  of the sex chromosome systems in relation with a kind of the sex chromosome systems within this family. Furthermore, the terminal location of NOR in the largest autosomal pair allowed us to use it as a chromosome marker and, thus, to infer that the kinetic activity of both ends is not a random process, and there is an inversion of this activity.

  1. C-heterochromatin and extra (B) chromosome distribution in six species of the Nabis (Heteroptera, Nabidae) with the modal male karyotype 2n = 16 + XY.

    Science.gov (United States)

    Grozeva, Snejana; Nokkala, Seppo

    2003-01-01

    The basic male karyotype of the six Nabis species (Heteroptera, Nabidae) is confirmed as being 2n=16+XY. The chromosomes are holokinetic while male meiosis is achiasmatic. The sex chromosomes undergo postreduction and in second metaphase show distance pairing, registered in all nabid species examined so far. Using C-banding technique for the first time in the family Nabidae, the heterochromatin was revealed on chromosomes of six species. The species showed different amount and distribution of C-heterochromatin. Only in Nabis (Dolichonabis) limbatus did the C-bands distribution make possible the identification of every chromosome pair in the karyotype. In other species, C-bands were found in some of the autosomes and the X, localized either interstitially or at telomeres. Only the Y usually showed relative stability ofthe C-banding pattern. In four of six species, extra (B) chromosomes were observed and their behaviour in meiosis described.

  2. The replication timing program of the Chinese hamster ?-globin locus is established coincident with its repositioning near peripheral heterochromatin in early G1 phase

    OpenAIRE

    Li, Feng; Chen, Jianhua; Izumi, Masako; Butler, Mark C.; Keezer, Susan M.; Gilbert, David M.

    2001-01-01

    We have examined the dynamics of nuclear repositioning and the establishment of a replication timing program for the actively transcribed dihydrofolate reductase (DHFR) locus and the silent ?-globin gene locus in Chinese hamster ovary cells. The DHFR locus was internally localized and replicated early, whereas the ?-globin locus was localized adjacent to the nuclear periphery and replicated during the middle of S phase, coincident with replication of peripheral heterochromatin. Nuclei were pr...

  3. Heterochromatin marks HP1gamma, HP1alpha and H3K9me3, and DNA damage response activation in human testis development and germ cell tumours

    Czech Academy of Sciences Publication Activity Database

    Bartkova, J.; Moudrý, Pavel; Hodný, Zdeněk; Lukas, J.; Rajpert-De Meyts, E.; Bartek, Jiří

    2011-01-01

    Roč. 34, 4 Pt 2 (2011), e103-e113 ISSN 0105-6263 R&D Projects: GA ČR GA301/08/0353 Grant - others:Lundbeck Foundation(DK) R13-A1287; EU FP7(XE) TRIREME 223575 Institutional research plan: CEZ:AV0Z50520514 Keywords : heterochromatinization * DNA damage response * germinal tumours Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.591, year: 2011

  4. Molecular cloning and characterization of satellite DNA sequences from constitutive heterochromatin of the habu snake (Protobothrops flavoviridis, Viperidae) and the Burmese python (Python bivittatus, Pythonidae).

    Science.gov (United States)

    Matsubara, Kazumi; Uno, Yoshinobu; Srikulnath, Kornsorn; Seki, Risako; Nishida, Chizuko; Matsuda, Yoichi

    2015-12-01

    Highly repetitive DNA sequences of the centromeric heterochromatin provide valuable molecular cytogenetic markers for the investigation of genomic compartmentalization in the macrochromosomes and microchromosomes of sauropsids. Here, the relationship between centromeric heterochromatin and karyotype evolution was examined using cloned repetitive DNA sequences from two snake species, the habu snake (Protobothrops flavoviridis, Crotalinae, Viperidae) and Burmese python (Python bivittatus, Pythonidae). Three satellite DNA (stDNA) families were isolated from the heterochromatin of these snakes: 168-bp PFL-MspI from P. flavoviridis and 196-bp PBI-DdeI and 174-bp PBI-MspI from P. bivittatus. The PFL-MspI and PBI-DdeI sequences were localized to the centromeric regions of most chromosomes in the respective species, suggesting that the two sequences were the major components of the centromeric heterochromatin in these organisms. The PBI-MspI sequence was localized to the pericentromeric region of four chromosome pairs. The PFL-MspI and the PBI-DdeI sequences were conserved only in the genome of closely related species, Gloydius blomhoffii (Crotalinae) and Python molurus, respectively, although their locations on the chromosomes were slightly different. In contrast, the PBI-MspI sequence was also in the genomes of P. molurus and Boa constrictor (Boidae), and additionally localized to the centromeric regions of eight chromosome pairs in B. constrictor, suggesting that this sequence originated in the genome of a common ancestor of Pythonidae and Boidae, approximately 86 million years ago. The three stDNA sequences showed no genomic compartmentalization between the macrochromosomes and microchromosomes, suggesting that homogenization of the centromeric and/or pericentromeric stDNA sequences occurred in the macrochromosomes and microchromosomes of these snakes.

  5. The replication timing program of the Chinese hamster β-globin locus is established coincident with its repositioning near peripheral heterochromatin in early G1 phase

    Science.gov (United States)

    Li, Feng; Chen, Jianhua; Izumi, Masako; Butler, Mark C.; Keezer, Susan M.; Gilbert, David M.

    2001-01-01

    We have examined the dynamics of nuclear repositioning and the establishment of a replication timing program for the actively transcribed dihydrofolate reductase (DHFR) locus and the silent β-globin gene locus in Chinese hamster ovary cells. The DHFR locus was internally localized and replicated early, whereas the β-globin locus was localized adjacent to the nuclear periphery and replicated during the middle of S phase, coincident with replication of peripheral heterochromatin. Nuclei were prepared from cells synchronized at various times during early G1 phase and stimulated to enter S phase by introduction into Xenopus egg extracts, and the timing of DHFR and β-globin replication was evaluated in vitro. With nuclei isolated 1 h after mitosis, neither locus was preferentially replicated before the other. However, with nuclei isolated 2 or 3 h after mitosis, there was a strong preference for replication of DHFR before β-globin. Measurements of the distance of DHFR and β-globin to the nuclear periphery revealed that the repositioning of the β-globin locus adjacent to peripheral heterochromatin also took place between 1 and 2 h after mitosis. These results suggest that the CHO β-globin locus acquires the replication timing program of peripheral heterochromatin upon association with the peripheral subnuclear compartment during early G1 phase. PMID:11470818

  6. Karyotypes, constitutive heterochromatin, and genomic DNA values in the blowfly genera Chrysomya, Lucilia, and Protophormia (Diptera: Calliphoridae).

    Science.gov (United States)

    Ullerich, Fritz-Helmut; Schöttke, Michael

    2006-06-01

    The karyotypes and C-banding patterns of Chrysomya species C. marginalis, C. phaonis, C. pinguis, C. saffranea, C. megacephala (New Guinean strain), Lucilia sericata, and Protophormia terraenovae are described. All species are amphogenic and have similar chromosome complements (2n = 12), including an XY-XX sex-chromosome pair varying in size and morphology between species. Additionally, the C-banding pattern of the monogenic species Chrysomya albiceps is presented. The DNA contents of these and of further species Chrysomya rufifacies, Chrysomya varipes, and Chrysomya putoria were assessed on mitotic metaphases by Feulgen cytophotometry. The average 2C DNA value of the male genomes ranged from 1.04 pg in C. varipes to 2.31 pg in C. pinguis. The DNA content of metaphase X chromosomes varied from 0.013 pg (= 1.23% of the total genome) in C. varipes to 0.277 pg (12.20%) in L. sericata; that of Y chromosomes ranged from 0.003 pg (0.27%) in C. varipes to 0.104 pg (5.59%) in L. sericata. In most species, the corresponding 5 large chromosome pairs showed similar relative DNA contents. The data suggest that the interspecific DNA differences in most species are mainly due to quantitative variation of (repetitive) sequences lying outside the centromeric heterochromatin blocks of the large chromosomes. The results are also discussed with regard to phylogenetic relationships of some species.

  7. The SUV39H1 Protein Lysine Methyltransferase Methylates Chromatin Proteins Involved in Heterochromatin Formation and VDJ Recombination.

    Science.gov (United States)

    Kudithipudi, Srikanth; Schuhmacher, Maren Kirstin; Kebede, Adam Fiseha; Jeltsch, Albert

    2017-04-21

    SUV39H1 is an H3K9 methyltransferase involved in the formation of heterochromatin. We investigated its substrate specificity profile and show recognition of H3 residues between K4 and G12 with highly specific readout of R8. The specificity profile of SUV39H1 is distinct from its paralog SUV39H2, indicating that they can have different additional substrates. Using the specificity profile, several novel SUV39H1 candidate substrates were identified. We observed methylation of 19 novel substrates at the peptide level and for six of them at the protein level. Methylation of RAG2, SET8, and DOT1L was confirmed in cells, which all have important roles in chromatin regulation. Methylation of SET8 allosterically stimulates its H4K20 monomethylation activity connecting SUV39H1 to the generation of increased H4K20me3 levels, another heterochromatic modification. Methylation of RAG2 alters its subnuclear localization, indicating that SUV39H1 might regulate VDJ recombination. Taken together, our results indicate that beyond the generation of H3K9me3, SUV39H1 has additional roles in chromatin biology by direct stimulation of the establishment of H4K20me3 and the regulation of chromatin binding of RAG2.

  8. Quantitative 3D Analysis of Nuclear Morphology and Heterochromatin Organization from Whole-Mount Plant Tissue Using NucleusJ.

    Science.gov (United States)

    Desset, Sophie; Poulet, Axel; Tatout, Christophe

    2018-01-01

    Image analysis is a classical way to study nuclear organization. While nuclear organization used to be investigated by colorimetric or fluorescent labeling of DNA or specific nuclear compartments, new methods in microscopy imaging now enable qualitative and quantitative analyses of chromatin pattern, and nuclear size and shape. Several procedures have been developed to prepare samples in order to collect 3D images for the analysis of spatial chromatin organization, but only few preserve the positional information of the cell within its tissue context. Here, we describe a whole mount tissue preparation procedure coupled to DNA staining using the PicoGreen ® intercalating agent suitable for image analysis of the nucleus in living and fixed tissues. 3D Image analysis is then performed using NucleusJ, an open source ImageJ plugin, which allows for quantifying variations in nuclear morphology such as nuclear volume, sphericity, elongation, and flatness as well as in heterochromatin content and position in respect to the nuclear periphery.

  9. A histone H3K9M mutation traps histone methyltransferase Clr4 to prevent heterochromatin spreading

    Energy Technology Data Exchange (ETDEWEB)

    Shan, Chun-Min; Wang, Jiyong; Xu, Ke; Chen, Huijie; Yue, Jia-Xing; Andrews, Stuart; Moresco, James J.; Yates, John R.; Nagy, Peter L.; Tong, Liang; Jia, Songtao

    2016-09-20

    Histone lysine-to-methionine (K-to-M) mutations are associated with multiple cancers, and they function in a dominant fashion to block the methylation of corresponding lysines on wild type histones. However, their mechanisms of function are controversial. Here we show that in fission yeast, introducing the K9M mutation into one of the three histone H3 genes dominantly blocks H3K9 methylation on wild type H3 across the genome. In addition, H3K9M enhances the interaction of histone H3 tail with the H3K9 methyltransferase Clr4 in a SAM (S-adenosyl-methionine)-dependent manner, and Clr4 is trapped at nucleation sites to prevent its spreading and the formation of large heterochromatin domains. We further determined the crystal structure of an H3K9M peptide in complex with human H3K9 methyltransferase G9a and SAM, which reveales that the methionine side chain had enhanced van der Waals interactions with G9a. Therefore, our results provide a detailed mechanism by which H3K9M regulates H3K9 methylation.

  10. Ommexecha virens (Thunberg, 1824) and Descampsacris serrulatum (Serville, 1831) (Orthoptera, Ommexechidae): karyotypes, constitutive heterochromatin and nucleolar organizing regions.

    Science.gov (United States)

    Carvalho, D B; Rocha, M F; Loreto, V; Silva, A E B; Souza, M J

    2011-01-01

    Chromosomes of Ommexecha virens and Descampsacris serrulatum (Ommexechidae) were analyzed through conventional staining, C-banding, base specific fluorochromes, silver nitrate impregnation (AgNO3), and fluorescent in situ hybridization (FISH) with probe for 45S rDNA. The two species presented diploid number 2n= 23,X0 in males and acrocentric autosomes, except the pair one that presented submetacentric morphology. The X chromosome has distinct morphology in the two analyzed species, being a medium acrocentric in Ommexecha virens and large submetacentric in Descampsacris serrulatum. The C-banding revealed pericentromeric blocks of constitutive heterochromatin (CH) in all the chromosomes of Descampsacris serrulatum. For Ommexecha virens it was evidenced that the blocks of CH are preferentially located in the pericentromeric area (however some bivalents presents additional blocks) or in different positions. The staining with CMA3/DA/DAPI showed GC rich CH blocks (CMA3+) in some chromosomes of the two species. The nucleolar organizer regions (NORs) were located in the bivalents L2, S9, S10 of Ommexecha virens and M5, M6, M7, S11 of Descampsacris serrulatum. The FISH for rDNA showed coincident results with the pattern of active NORs revealed by AgNO3. This work presents the first chromosomal data, obtained through differential cytogenetics techniques in Ommexechidae, contributing to a better characterization of karyotypic evolution for this grasshopper family.

  11. Dependence of stratocumulus-topped boundary-layer entrainment on cloud-water sedimentation: Impact on global aerosol indirect effect in GISS ModelE3 single column model and global simulations

    Science.gov (United States)

    Ackerman, A. S.; Kelley, M.; Cheng, Y.; Fridlind, A. M.; Del Genio, A. D.; Bauer, S.

    2017-12-01

    Reduction in cloud-water sedimentation induced by increasing droplet concentrations has been shown in large-eddy simulations (LES) and direct numerical simulation (DNS) to enhance boundary-layer entrainment, thereby reducing cloud liquid water path and offsetting the Twomey effect when the overlying air is sufficiently dry, which is typical. Among recent upgrades to ModelE3, the latest version of the NASA Goddard Institute for Space Studies (GISS) general circulation model (GCM), are a two-moment stratiform cloud microphysics treatment with prognostic precipitation and a moist turbulence scheme that includes an option in its entrainment closure of a simple parameterization for the effect of cloud-water sedimentation. Single column model (SCM) simulations are compared to LES results for a stratocumulus case study and show that invoking the sedimentation-entrainment parameterization option indeed reduces the dependence of cloud liquid water path on increasing aerosol concentrations. Impacts of variations of the SCM configuration and the sedimentation-entrainment parameterization will be explored. Its impact on global aerosol indirect forcing in the framework of idealized atmospheric GCM simulations will also be assessed.

  12. Neutron and x-ray scattering study of phonon dispersion and diffuse scattering in (Na ,Bi ) Ti O3-x BaTi O3 single crystals near the morphotropic phase boundary

    Science.gov (United States)

    Luo, Chengtao; Bansal, Dipanshu; Li, Jiefang; Viehland, Dwight; Winn, Barry; Ren, Yang; Li, Xiaobing; Luo, Haosu; Delaire, Olivier

    2017-11-01

    Neutron and x-ray scattering measurements were performed on (N a1 /2B i1 /2 ) Ti O3-x at %BaTi O3 (NBT-x BT ) single crystals (x =4 , 5, 6.5, and 7.5) across the morphotropic phase boundary (MPB), as a function of both composition and temperature, and probing both structural and dynamical aspects. In addition to the known diffuse scattering pattern near the Γ points, our measurements revealed new, faint superlattice peaks, as well as an extensive diffuse scattering network, revealing a short-range ordering of polar nanoregions (PNR) with a static stacking morphology. In samples with compositions closest to the MPB, our inelastic neutron scattering investigations of the phonon dynamics showed two unusual features in the acoustic phonon branches, between the superlattice points, and between the superlattice points and Γ points, respectively. These critical elements are not present in the other compositions away from the MPB, which suggests that these features may be related to the tilt modes coupling behavior near the MPB.

  13. Rigid supersymmetry with boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Belyaev, D.V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Van Nieuwenhuizen, P. [State Univ. of New York, Stony Brook, NY (United States). C.N. Yang Inst. for Theoretical Physics

    2008-01-15

    We construct rigidly supersymmetric bulk-plus-boundary actions, both in x-space and in superspace. For each standard supersymmetric bulk action a minimal supersymmetric bulk-plus-boundary action follows from an extended F- or D-term formula. Additional separately supersymmetric boundary actions can be systematically constructed using co-dimension one multiplets (boundary superfields). We also discuss the orbit of boundary conditions which follow from the Euler-Lagrange variational principle. (orig.)

  14. Rigid supersymmetry with boundaries

    International Nuclear Information System (INIS)

    Belyaev, D.V.; Van Nieuwenhuizen, P.

    2008-01-01

    We construct rigidly supersymmetric bulk-plus-boundary actions, both in x-space and in superspace. For each standard supersymmetric bulk action a minimal supersymmetric bulk-plus-boundary action follows from an extended F- or D-term formula. Additional separately supersymmetric boundary actions can be systematically constructed using co-dimension one multiplets (boundary superfields). We also discuss the orbit of boundary conditions which follow from the Euler-Lagrange variational principle. (orig.)

  15. Molecular Cytogenetics in Trough Shells (Mactridae, Bivalvia: Divergent GC-Rich Heterochromatin Content

    Directory of Open Access Journals (Sweden)

    Daniel García-Souto

    2016-08-01

    Full Text Available The family Mactridae is composed of a diverse group of marine organisms, commonly known as trough shells or surf clams, which illustrate a global distribution. Although this family includes some of the most fished and cultured bivalve species, their chromosomes are poorly studied. In this work, we analyzed the chromosomes of Spisula solida, Spisula subtruncata and Mactra stultorum by means of fluorochrome staining, C-banding and fluorescent in situ hybridization using 28S ribosomal DNA (rDNA, 5S rDNA, H3 histone gene and telomeric probes. All three trough shells presented 2n = 38 chromosomes but different karyotype compositions. As happens in most bivalves, GC-rich regions were limited to the nucleolus organizing regions in Spisula solida. In contrast, many GC-rich heterochromatic bands were detected in both Spisula subtruncata and Mactra stultorum. Although the three trough shells presented single 5S rDNA and H3 histone gene clusters, their chromosomal locations differed. Regarding major rDNA clusters, while Spisula subtruncata presented a single cluster, both Spisula solida and Mactra stultorum showed two. No evidence of intercalary telomeric signals was detected in these species. The molecular cytogenetic characterization of these taxa will contribute to understanding the role played by chromosome changes in the evolution of trough shells.

  16. Genetic fidelity assessment in micropropagated plants using cytogenetical analysis and heterochromatin distribution: a case study with Nepenthes khasiana Hook f.

    Science.gov (United States)

    Devi, Soibam Purnima; Kumaria, Suman; Rao, Satyawada Rama; Tandon, Pramod

    2015-09-01

    Rapid clonal propagation of selected genotypes has been one of the most extensively exploited approaches of biotechnology. However, inclusion of somaclonal variations in tissue-culture-derived plants results in the production of undesirable plant off-types which limits its applications in tissue culture industry. Therefore, the most critical concern has been the maintenance of genetic uniformity of micropropagated plants. Assessment of genetic fidelity in tissue-culture-raised plants of three consecutive regenerations of Nepenthes khasiana has been successfully carried out using chromosome counts and heterochromatin distribution pattern wherein changes in the number of chromosomes and the distribution of AT and GC base pairs were recorded. The cells studied in the plantlets of the first regeneration (23.33 %) showed deviant number of chromosome which was increased to 33.33 % and 40 % in the plantlets of the second and the third regenerations, respectively. Also, 4',6-diamidino-2-phenylindole (DAPI)(+) and chromomycin A3 (CMA)(+) binding sites, on an average of 5.74 ± 0.47 and 5.00 ± 0.30, were observed in the plantlets of the first regeneration. Subsequently, DAPI(+) binding sites were increased to 6.61 ± 0.39 and 6.74 ± 0.57 in the plantlets of the second and the third regenerations, respectively, with a corresponding decrease in the CMA(+) binding sites (4.63 ± 0.45 and 4.16 ± 0.47 CMA(+) sites in the plantlets of the second and the third regenerations, respectively). The study reveals an increase in cytological variations in the morphologically similar micropropagated plants of N. khasiana with the subsequent regenerations which further necessitate the determination of genetic integrity of micropropagated plants.

  17. The new boundaries of the "boundaryless" company.

    Science.gov (United States)

    Hirschhorn, L; Gilmore, T

    1992-01-01

    In an economy founded on innovation and change, one of the premier challenges of management is to design more flexible organizations. For many executives, a single metaphor has come to embody this managerial challenge and to capture the kind of organization they want to create: the "corporation without boundaries." According to Larry Hirschhorn and Thomas Gilmore of the Wharton Center for Applied Research, managers are right to break down the boundaries that make organizations rigid and unresponsive. But they are wrong if they think that doing so eliminates the need for boundaries altogether. Once the traditional boundaries of hierarchy, function, and geography disappear, a new set of boundaries becomes important. These new boundaries are more psychological than organizational. They aren't drawn on a company's organizational chart but in the minds of its managers and employees. And instead of being reflected in a company's structure, they must be "enacted" over and over again in a manager's relationships with bosses, subordinates, and peers. In this article, Hirschhorn and Gilmore provide a guide to the boundaries that matter in the "boundaryless" company. They explain how these new boundaries are essential for both managers and employees in coping with the demands of flexible work. They describe the typical mistakes that managers make in their boundary relationships. And they show how executives can become effective boundary managers by paying attention to a source of data they have often overlooked in the past: their own gut feelings about work and the people with whom they do it.

  18. Allegheny County Municipal Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the municipal boundaries in Allegheny County. Data was created to portray the boundaries of the 130 Municipalities in Allegheny County the...

  19. HUD GIS Boundary Files

    Data.gov (United States)

    Department of Housing and Urban Development — The HUD GIS Boundary Files are intended to supplement boundary files available from the U.S. Census Bureau. The files are for community planners interested in...

  20. State Agency Administrative Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This database comprises 28 State agency boundaries and point of contact. The Kansas Geological Survey collected legal descriptions of the boundaries for various...

  1. Political State Boundary (National)

    Data.gov (United States)

    Department of Transportation — State boundaries with political limit - boundaries extending into the ocean (NTAD). The TIGER/Line Files are shapefiles and related database files (.dbf) that are an...

  2. Environmentalists without Boundaries

    African Journals Online (AJOL)

    GREGORY

    2009-03-16

    Mar 16, 2009 ... Environmentalists without Boundaries. Setting Boundaries is a popular strategy in child development programs. But as children mature into young adults, it dawns on many that certain boundaries must be crossed to explore rich opportunities outside the safe closet of their teachers or parents' watchful eyes.

  3. Boundary denoising for open surface meshes

    Science.gov (United States)

    Lee, Wei Zhe; Lim, Wee Keong; Soo, Wooi King

    2013-04-01

    Recently, applications of open surfaces in 3D have emerged to be an interesting research topic due to the popularity of range cameras such as the Microsoft Kinect. However, surface meshes representing such open surfaces are often corrupted with noises especially at the boundary. Such deformity needs to be treated to facilitate further applications such as texture mapping and zippering of multiple open surface meshes. Conventional methods perform denoising by removing components with high frequencies, thus smoothing the boundaries. However, this may result in loss of information, as not all high frequency transitions at the boundaries correspond to noises. To overcome such shortcoming, we propose a combination of local information and geometric features to single out the noises or unusual vertices at the mesh boundaries. The local shape of the selected mesh boundaries regions, characterized by the mean curvature value, is compared with that of the neighbouring interior region. The neighbouring interior region is chosen such that it is the closest to the corresponding boundary region, while curvature evaluation is independent of the boundary. The smoothing processing is done via Laplacian smoothing with our modified weights to reduce boundary shrinkage. The evaluation of the algorithm is done by noisy meshes generated from controlled model clean meshes. The Hausdorff distance is used as the measurement between the meshes. We show that our method produces better results than conventional smoothing of the whole boundary loop.

  4. Technology for Boundaries

    DEFF Research Database (Denmark)

    Bødker, Susanne; Kristensen, Jannie Friis; Nielsen, Christina

    2003-01-01

    This paper presents a study of an organisation, which is undergoing a process transforming organisational and technological boundaries. In particular, we shall look at three kinds of boundaries: the work to maintain and change the boundary between the organisation and its customers; boundaries...... between competencies within the organisation; and boundaries between various physical locations of work, in particular between what is done in the office and what is done on site. Maintaining and changing boundaries are the processes through which a particular community sustains its identity and practice...... on the one hand, and where it is confronted with the identity and practices on the other.The organisation being studied employs a multitude of IT systems that support and maintain these boundaries in a particular manner that are in many ways inappropriate to the current needs of the organisation...

  5. Characterizations of boundary pluripolar hulls

    NARCIS (Netherlands)

    Djire, I.K.; Wiegerinck, J.

    2016-01-01

    We present some basic properties of the so-called boundary relative extremal function and discuss boundary pluripolar sets and boundary pluripolar hulls. We show that for B-regular domains the boundary pluripolar hull is always trivial on the boundary of the domain and present a “boundary version”

  6. Live-cell imaging of HP1α throughout the cell cycle of mouse C3H10T1/2 cells and rhythmical flickering of heterochromatin dots in interphase.

    Science.gov (United States)

    Nakagawa, Chika; Kawakita, Ai; Fukada, Takashi; Sugimoto, Kenji

    2014-01-01

    Heterochromatin protein 1 alpha (HP1α) localizes to heterochromatin in interphase and shows dynamic molecular behavior in living cells. We previously reported that during mitosis, the majority of HP1α diffused into the cytoplasm but some remained in centromere heterochromatin. Here, we further characterize the molecular behavior of HP1α throughout the cell cycle. Time-lapse imaging of DsRed-HP1α through two successive cell divisions indicated that interphase can be divided into four phases. HP1α forms heterochromatin dots in early G1, which are maintained without any apparent changes (Phase 1). However, the HP1α dots begin to diffuse into the nucleoplasm and start flickering with a rhythmical cycle (Phase 2). Then, the HP1α dots diffuse further towards the periphery of the nucleus (Phase 3), and uniformly diffuse throughout the entire nucleus (Phase 4). Rhythmical flickering of HP1α dots in the middle of interphase may be useful for following cell cycle progression in mouse living cells.

  7. Microsatellite distribution on sex chromosomes at different stages of heteromorphism and heterochromatinization in two lizard species (Squamata: Eublepharidae: Coleonyx elegans and Lacertidae: Eremias velox

    Directory of Open Access Journals (Sweden)

    Kratochvíl Lukáš

    2011-10-01

    Full Text Available Abstract Background The accumulation of repetitive sequences such as microsatellites during the differentiation of sex chromosomes has not been studied in most squamate reptiles (lizards, amphisbaenians and snakes, a group which has a large diversity of sex determining systems. It is known that the Bkm repeats containing tandem arrays of GATA tetranucleotides are highly accumulated on the degenerated W chromosomes in advanced snakes. Similar, potentially homologous, repetitive sequences were found on sex chromosomes in other vertebrates. Using FISH with probes containing all possible mono-, di-, and tri-nucleotide sequences and GATA, we studied the genome distribution of microsatellite repeats on sex chromosomes in two lizard species (the gecko Coleonyx elegans and the lacertid Eremias velox with independently evolved sex chromosomes. The gecko possesses heteromorphic euchromatic sex chromosomes, while sex chromosomes in the lacertid are homomorphic and the W chromosome is highly heterochromatic. Our aim was to test whether microsatellite distribution on sex chromosomes corresponds to the stage of their heteromorphism or heterochromatinization. Moreover, because the lizards lie phylogenetically between snakes and other vertebrates with the Bkm-related repeats on sex chromosomes, the knowledge of their repetitive sequence is informative for the determination of conserved versus convergently evolved repetitive sequences across vertebrate lineages. Results Heteromorphic sex chromosomes of C. elegans do not show any sign of microsatellite accumulation. On the other hand, in E. velox, certain microsatellite sequences are extensively accumulated over the whole length or parts of the W chromosome, while others, including GATA, are absent on this heterochromatinized sex chromosome. Conclusion The accumulation of microsatellite repeats corresponds to the stage of heterochromatinization of sex chromosomes rather than to their heteromorphism. The lack of

  8. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  9. Development of boundary layers

    International Nuclear Information System (INIS)

    Herbst, R.

    1980-01-01

    Boundary layers develop along the blade surfaces on both the pressure and the suction side in a non-stationary flow field. This is due to the fact that there is a strongly fluctuating flow on the downstream blade row, especially as a result of the wakes of the upstream blade row. The author investigates the formation of boundary layers under non-stationary flow conditions and tries to establish a model describing the non-stationary boundary layer. For this purpose, plate boundary layers are measured, at constant flow rates but different interferent frequency and variable pressure gradients. By introducing the sample technique, measurements of the non-stationary boundary layer become possible, and the flow rate fluctuation can be divided in its components, i.e. stochastic turbulence and periodical fluctuation. (GL) [de

  10. Event boundaries and memory improvement.

    Science.gov (United States)

    Pettijohn, Kyle A; Thompson, Alexis N; Tamplin, Andrea K; Krawietz, Sabine A; Radvansky, Gabriel A

    2016-03-01

    The structure of events can influence later memory for information that is embedded in them, with evidence indicating that event boundaries can both impair and enhance memory. The current study explored whether the presence of event boundaries during encoding can structure information to improve memory. In Experiment 1, memory for a list of words was tested in which event structure was manipulated by having participants walk through a doorway, or not, halfway through the word list. In Experiment 2, memory for lists of words was tested in which event structure was manipulated using computer windows. Finally, in Experiments 3 and 4, event structure was manipulated by having event shifts described in narrative texts. The consistent finding across all of these methods and materials was that memory was better when the information was distributed across two events rather than combined into a single event. Moreover, Experiment 4 demonstrated that increasing the number of event boundaries from one to two increased the memory benefit. These results are interpreted in the context of the Event Horizon Model of event cognition. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Repeat Composition of CenH3-chromatin and H3K9me2-marked heterochromatin in Sugar Beet (Beta vulgaris).

    Science.gov (United States)

    Kowar, Teresa; Zakrzewski, Falk; Macas, Jiří; Kobližková, Andrea; Viehoever, Prisca; Weisshaar, Bernd; Schmidt, Thomas

    2016-05-26

    Sugar beet (Beta vulgaris) is an important crop of temperate climate zones, which provides nearly 30 % of the world's annual sugar needs. From the total genome size of 758 Mb, only 567 Mb were incorporated in the recently published genome sequence, due to the fact that regions with high repetitive DNA contents (e.g. satellite DNAs) are only partially included. Therefore, to fill these gaps and to gain information about the repeat composition of centromeres and heterochromatic regions, we performed chromatin immunoprecipitation followed by sequencing (ChIP-Seq) using antibodies against the centromere-specific histone H3 variant of sugar beet (CenH3) and the heterochromatic mark of dimethylated lysine 9 of histone H3 (H3K9me2). ChIP-Seq analysis revealed that active centromeres containing CenH3 consist of the satellite pBV and the Ty3-gypsy retrotransposon Beetle7, while heterochromatin marked by H3K9me2 exhibits heterogeneity in repeat composition. H3K9me2 was mainly associated with the satellite family pEV, the Ty1-copia retrotransposon family Cotzilla and the DNA transposon superfamily of the En/Spm type. In members of the section Beta within the genus Beta, immunostaining using the CenH3 antibody was successful, indicating that orthologous CenH3 proteins are present in closely related species within this section. The identification of repetitive genome portions by ChIP-Seq experiments complemented the sugar beet reference sequence by providing insights into the repeat composition of poorly characterized CenH3-chromatin and H3K9me2-heterochromatin. Therefore, our work provides the basis for future research and application concerning the sugar beet centromere and repeat-rich heterochromatic regions characterized by the presence of H3K9me2.

  12. RNA-binding protein regulates plant DNA methylation by controlling mRNA processing at the intronic heterochromatin-containing gene IBM1.

    Science.gov (United States)

    Wang, Xingang; Duan, Cheng-Guo; Tang, Kai; Wang, Bangshing; Zhang, Huiming; Lei, Mingguang; Lu, Kun; Mangrauthia, Satendra K; Wang, Pengcheng; Zhu, Guohui; Zhao, Yang; Zhu, Jian-Kang

    2013-09-17

    DNA methylation-dependent heterochromatin formation is a conserved mechanism of epigenetic silencing of transposons and other repeat elements in many higher eukaryotes. Genes adjacent to repetitive elements are often also subjected to this epigenetic silencing. Consequently, plants have evolved antisilencing mechanisms such as active DNA demethylation mediated by the REPRESSOR OF SILENCING 1 (ROS1) family of 5-methylcytosine DNA glycosylases to protect these genes from silencing. Some transposons and other repeat elements have found residence in the introns of genes. It is unclear how these intronic repeat elements-containing genes are regulated. We report here the identification of ANTI-SILENCING 1 (ASI1), a bromo-adjacent homology domain and RNA recognition motif-containing protein, from a forward genetic screen for cellular antisilencing factors in Arabidopsis thaliana. ASI1 is required to prevent promoter DNA hypermethylation and transcriptional silencing of some transgenes. Genome-wide DNA methylation analysis reveals that ASI1 has a similar role to that of the histone H3K9 demethylase INCREASE IN BONSAI METHYLATION 1 (IBM1) in preventing CHG methylation in the bodies of thousands of genes. We found that ASI1 is an RNA-binding protein and ensures the proper expression of IBM1 full-length transcript by associating with an intronic heterochromatic repeat element of IBM1. Through mRNA sequencing, we identified many genes containing intronic transposon elements that require ASI1 for proper expression. Our results suggest that ASI1 associates with intronic heterochromatin and binds the gene transcripts to promote their 3' distal polyadenylation. The study thus reveals a unique mechanism by which higher eukaryotes deal with the collateral effect of silencing intronic repeat elements.

  13. Unraveling the karyotype structure of the spurges Euphorbia hirta Linnaeus, 1753 and E. hyssopifolia Linnaeus, 1753 (Euphorbiaceae) using genome size estimation and heterochromatin differentiation

    Science.gov (United States)

    Santana, Karla C. B.; Pinangé, Diego S. B.; Vasconcelos, Santelmo; Oliveira, Ana R.; Brasileiro-Vidal, Ana C.; Alves, Marccus V.; Benko-Iseppon, Ana M.

    2016-01-01

    Abstract Euphorbia Linnaeus, 1753 (Euphorbiaceae) is one of the most diverse and complex genera among the angiosperms, showing a huge diversity in morphologic traits and ecologic patterns. In order to improve the knowledge of the karyotype organization of Euphorbia hirta (2n = 18) and Euphorbia hyssopifolia (2n = 12), cytogenetic studies were performed by means of conventional staining with Giemsa, genome size estimations with flow cytometry, heterochromatin differentiation with chromomycin A3 (CMA) and 4’,6-diamidino-2-phenylindole (DAPI) and Giemsa C-banding, fluorescent in situ hybridization (FISH) with 45S and 5S rDNA probes, and impregnation with silver nitrate (AgNO3). Our results revealed small metacentric chromosomes, CMA+/DAPI0 heterochromatin in the pericentromeric regions of all chromosomes and CMA+/DAPI− in the distal part of chromosome arms carriers of nucleolar organizing regions (NORs). The DNA content measurements revealed small genomes for both species: Euphorbia hirta with 2C = 0.77 pg and Euphorbia hyssopifolia with 2C = 1.41 pg. After FISH procedures, Euphorbia hirta, and Euphorbia hyssopifolia presented three and four pairs of terminal 45S rDNA sites, respectively, colocalizing with CMA+ heterochromatic blocks, besides only one interstitial pair of 5S rDNA signals. Additionally, the maximum number of active NORs agreed with the total number of observed 45S rDNA sites. This work represents the first analysis using FISH in the subfamily Euphorbioideae, revealing a significant number of chromosomal markers, which may be very helpful to understand evolutionary patterns among Euphorbia species. PMID:28123686

  14. Unraveling the karyotype structure of the spurgesEuphorbia hirtaLinnaeus, 1753 andE. hyssopifoliaLinnaeus, 1753 (Euphorbiaceae) using genome size estimation and heterochromatin differentiation.

    Science.gov (United States)

    Santana, Karla C B; Pinangé, Diego S B; Vasconcelos, Santelmo; Oliveira, Ana R; Brasileiro-Vidal, Ana C; Alves, Marccus V; Benko-Iseppon, Ana M

    2016-01-01

    Euphorbia Linnaeus, 1753 (Euphorbiaceae) is one of the most diverse and complex genera among the angiosperms, showing a huge diversity in morphologic traits and ecologic patterns. In order to improve the knowledge of the karyotype organization of Euphorbia hirta (2n = 18) and Euphorbia hyssopifolia (2n = 12), cytogenetic studies were performed by means of conventional staining with Giemsa, genome size estimations with flow cytometry, heterochromatin differentiation with chromomycin A 3 (CMA) and 4',6-diamidino-2-phenylindole (DAPI) and Giemsa C-banding, fluorescent in situ hybridization (FISH) with 45S and 5S rDNA probes, and impregnation with silver nitrate (AgNO 3 ). Our results revealed small metacentric chromosomes, CMA + /DAPI 0 heterochromatin in the pericentromeric regions of all chromosomes and CMA + /DAPI - in the distal part of chromosome arms carriers of nucleolar organizing regions (NORs). The DNA content measurements revealed small genomes for both species: Euphorbia hirta with 2C = 0.77 pg and Euphorbia hyssopifolia with 2C = 1.41 pg. After FISH procedures, Euphorbia hirta , and Euphorbia hyssopifolia presented three and four pairs of terminal 45S rDNA sites, respectively, colocalizing with CMA + heterochromatic blocks, besides only one interstitial pair of 5S rDNA signals. Additionally, the maximum number of active NORs agreed with the total number of observed 45S rDNA sites. This work represents the first analysis using FISH in the subfamily Euphorbioideae, revealing a significant number of chromosomal markers, which may be very helpful to understand evolutionary patterns among Euphorbia species.

  15. Unraveling the karyotype structure of the spurges Euphorbia hirta Linnaeus, 1753 and E. hyssopifolia Linnaeus, 1753 (Euphorbiaceae using genome size estimation and heterochromatin differentiation

    Directory of Open Access Journals (Sweden)

    Karla C. B. Santana

    2016-12-01

    Full Text Available Euphorbia Linnaeus, 1753 (Euphorbiaceae is one of the most diverse and complex genera among the angiosperms, showing a huge diversity in morphologic traits and ecologic patterns. In order to improve the knowledge of the karyotype organization of Euphorbia hirta (2n = 18 and E. hyssopifolia (2n = 12, cytogenetic studies were performed by means of conventional staining with Giemsa, genome size estimations with flow cytometry, heterochromatin differentiation with chromomycin A3 (CMA and 4’,6-diamidino-2-phenylindole (DAPI and Giemsa C-banding, fluorescent in situ hybridization (FISH with 45S and 5S rDNA probes, and impregnation with silver nitrate (AgNO3. Our results revealed small metacentric chromosomes, CMA+/DAPI0 heterochromatin in the pericentromeric regions of all chromosomes and CMA+/DAPI− in the distal part of chromosome arms carriers of nucleolar organizing regions (NORs. The DNA content measurements revealed small genomes for both species: E. hirta with 2C = 0.77 pg and E. hyssopifolia with 2C = 1.41 pg. After FISH procedures, E. hirta, and E. hyssopifolia presented three and four pairs of terminal 45S rDNA sites, respectively, colocalizing with CMA+ heterochromatic blocks, besides only one interstitial pair of 5S rDNA signals. Additionally, the maximum number of active NORs agreed with the total number of observed 45S rDNA sites. This work represents the first analysis using FISH in the subfamily Euphorbioideae, revealing a significant number of chromosomal markers, which may be very helpful to understand evolutionary patterns among Euphorbia species.

  16. Administrative Area Boundaries 2 (State Boundaries), Region 9, 2010, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Administrative Area Boundaries 2 (State Boundaries) for Region 9. There are five Administrative Area Boundaries layers (1, 2, 3, 4, 5). These layers contain...

  17. Administrative Area Boundaries 4 (City Boundaries), Region 9, 2010, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Administrative Area Boundaries 4 (City Boundaries) for Region 9. There are five Administrative Area Boundaries layers (1, 2, 3, 4, 5). These layers contain...

  18. Beyond the Boundary

    DEFF Research Database (Denmark)

    Gorm Hansen, Birgitte

    2011-01-01

    Whether celebratory or critical, STS research on science-industry relations has focused on the blurring of boundaries and hybridization of codes and practices. However, the vocabulary of boundary and hybrid tends to reify science and industry as separate in the attempt to map their relation...... as the negotiation of a preexisting science-industry boundary. Rather, viability is obtained through a strategy of "circumventing" the science-industry food chain and "sequestering" biotech components within the research center. Symbiosis allows academic scientists to do biology while at the same time demonstrating...

  19. Allegheny County Parcel Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains parcel boundaries attributed with county block and lot number. Use the Property Information Extractor for more control downloading a filtered...

  20. Allegheny County Boundary

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains the Allegheny County boundary. If viewing this description on the Western Pennsylvania Regional Data Center’s open data portal...

  1. Boundary representation modelling techniques

    CERN Document Server

    2006-01-01

    Provides the most complete presentation of boundary representation solid modelling yet publishedOffers basic reference information for software developers, application developers and users Includes a historical perspective as well as giving a background for modern research.

  2. NM School District Boundaries

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The dataset represents the boundaries of all public school districts in the state of New Mexico. The source for the data layer is the New Mexico Public Education...

  3. Site Area Boundaries

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset consists of site boundaries from multiple Superfund sites in U.S. EPA Region 8. These data were acquired from multiple sources at different times and...

  4. Relationships, not boundaries.

    Science.gov (United States)

    Combs, Gene; Freedman, Jill

    2002-01-01

    The authors find it more useful to pay attention to relationships than to boundaries. By focusing attention on bounded, individual psychological issues, the metaphor of boundaries can distract helping professionals from thinking about inequities of power. It oversimplifies a complex issue, inviting us to ignore discourses around gender, race, class, culture, and the like that support injustice, abuse, and exploitation. Making boundaries a central metaphor for ethical practice can keep us from critically examining the effects of distance, withdrawal, and non-participation. The authors describe how it is possible to examine the practical, moral, and ethical effects of our participation in relationships by focusing on just relationships rather than on boundaries. They give illustrations and clinical examples of relationally-focused ethical practices that derive from a narrative approach to therapy.

  5. National Forest Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — This theme shows the USFS national forest boundaries in the state. This data was acquired from the GIS coordinators at both the Chippewa National Forest and the...

  6. HUC 8 Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This data set is a digital hydrologic unit boundary that is at the 4-digit, 6-digit, 8-digit, and 11-digit level. The data set was developed by delineating the...

  7. 500 Cities: City Boundaries

    Data.gov (United States)

    U.S. Department of Health & Human Services — This city boundary shapefile was extracted from Esri Data and Maps for ArcGIS 2014 - U.S. Populated Place Areas. This shapefile can be joined to 500 Cities...

  8. State Park Statutory Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — Legislative statutory boundaries for sixty six state parks, six state recreation areas, and eight state waysides. These data are derived principally from DNR's...

  9. Attraction, with Boundaries

    OpenAIRE

    Chakraborty, Avik; Krishnan, Chethan

    2012-01-01

    We study the basin of attraction of static extremal black holes, in the concrete setting of the STU model. By finding a connection to a decoupled Toda-like system and solving it exactly, we find a simple way to characterize the attraction basin via competing behaviors of certain parameters. The boundaries of attraction arise in the various limits where these parameters degenerate to zero. We find that these boundaries are generalizations of the recently introduced (extremal) subtracted geomet...

  10. Grain Boundary Complexions

    Science.gov (United States)

    2014-05-01

    complexion transitions occur often in doped titanates, such as BaTiO3 and SrTiO3, and have been utilized to tailor microstructural develop- ment [275,276...Cantwell et al. / Acta Materialia 62 (2014) 1–48 Despite decades of research, efforts to identify grain boundary complexion transitions in pure metals via...evidence suggesting grain boundary complexion transitions in pure metals has existed for decades. For example, researchers have reported anomalies and

  11. Senescence-associated heterochromatin foci are dispensable for cellular senescence, occur in a cell type- and insult-dependent manner, and follow expression of p16 (ink4a)

    Czech Academy of Sciences Publication Activity Database

    Košař, Martin; Bartkova, J.; Hubáčková, Soňa; Hodný, Zdeněk; Lukas, J.; Bartek, Jiří

    2011-01-01

    Roč. 10, č. 3 (2011), s. 457-468 ISSN 1538-4101 R&D Projects: GA ČR GA204/08/1418; GA ČR GA301/08/0353 Institutional research plan: CEZ:AV0Z50520514 Keywords : genotoxic and replicative stress * senescence-associated heterochromatin foci * DNA damage response Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.359, year: 2011

  12. The Bottom Boundary Layer

    Science.gov (United States)

    Trowbridge, John H.; Lentz, Steven J.

    2018-01-01

    The oceanic bottom boundary layer extracts energy and momentum from the overlying flow, mediates the fate of near-bottom substances, and generates bedforms that retard the flow and affect benthic processes. The bottom boundary layer is forced by winds, waves, tides, and buoyancy and is influenced by surface waves, internal waves, and stratification by heat, salt, and suspended sediments. This review focuses on the coastal ocean. The main points are that (a) classical turbulence concepts and modern turbulence parameterizations provide accurate representations of the structure and turbulent fluxes under conditions in which the underlying assumptions hold, (b) modern sensors and analyses enable high-quality direct or near-direct measurements of the turbulent fluxes and dissipation rates, and (c) the remaining challenges include the interaction of waves and currents with the erodible seabed, the impact of layer-scale two- and three-dimensional instabilities, and the role of the bottom boundary layer in shelf-slope exchange.

  13. Beyond the Boundary

    DEFF Research Database (Denmark)

    Gorm Hansen, Birgitte

    2012-01-01

    as the negotiation of a preexisting science-industry boundary. Rather, viability is obtained through a strategy of circumventing the science-industry food chain and sequestering biotech components within the research center. Symbiosis allows academic scientists to do biology while at the same time demonstrating......Whether celebratory or critical, STS research on science-industry relations has focused on the blurring of boundaries and hybridization of codes and practices. However, the vocabulary of boundary and hybrid tends to reify science and industry as separate in the attempt to map their relation....... Drawing on interviews with the head of a research center in plant biology, this article argues that biology and biotech are symbionts. In order to be viable and productive, symbiosis needs to be carefully managed and given room for divergence within mutual dependence. This process does not take place...

  14. Ubiquitin ligase RNF123 mediates degradation of heterochromatin protein 1α and β in lamin A/C knock-down cells.

    Directory of Open Access Journals (Sweden)

    Pankaj Chaturvedi

    Full Text Available The nuclear lamina is a key determinant of nuclear architecture, integrity and functionality in metazoan nuclei. Mutations in the human lamin A gene lead to highly debilitating genetic diseases termed as laminopathies. Expression of lamin A mutations or reduction in levels of endogenous A-type lamins leads to nuclear defects such as abnormal nuclear morphology and disorganization of heterochromatin. This is accompanied by increased proteasomal degradation of certain nuclear proteins such as emerin, nesprin-1α, retinoblastoma protein and heterochromatin protein 1 (HP1. However, the pathways of proteasomal degradation have not been well characterized.To investigate the mechanisms underlying the degradation of HP1 proteins upon lamin misexpression, we analyzed the effects of shRNA-mediated knock-down of lamins A and C in HeLa cells. Cells with reduced levels of expression of lamins A and C exhibited proteasomal degradation of HP1α and HP1β but not HP1γ. Since specific ubiquitin ligases are upregulated in lamin A/C knock-down cells, further studies were carried out with one of these ligases, RNF123, which has a putative HP1-binding motif. Ectopic expression of GFP-tagged RNF123 directly resulted in degradation of HP1α and HP1β. Mutational analysis showed that the canonical HP1-binding pentapeptide motif PXVXL in the N-terminus of RNF123 was required for binding to HP1 proteins and targeting them for degradation. The role of endogenous RNF123 in the degradation of HP1 isoforms was confirmed by RNF123 RNAi experiments. Furthermore, FRAP analysis suggested that HP1β was displaced from chromatin in laminopathic cells.Our data support a role for RNF123 ubiquitin ligase in the degradation of HP1α and HP1β upon lamin A/C knock-down. Hence lamin misexpression can cause degradation of mislocalized proteins involved in key nuclear processes by induction of specific components of the ubiquitin-proteasome system.

  15. The boundary is mixed

    Science.gov (United States)

    Bianchi, Eugenio; Haggard, Hal M.; Rovelli, Carlo

    2017-08-01

    We show that in Oeckl's boundary formalism the boundary vectors that do not have a tensor form represent, in a precise sense, statistical states. Therefore the formalism incorporates quantum statistical mechanics naturally. We formulate general-covariant quantum statistical mechanics in this language. We illustrate the formalism by showing how it accounts for the Unruh effect. We observe that the distinction between pure and mixed states weakens in the general covariant context, suggesting that local gravitational processes are naturally statistical without a sharp quantal versus probabilistic distinction.

  16. Minnesota County Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — Minnesota county boundaries derived from a combination of 1:24,000 scale PLS lines, 1:100,000 scale TIGER, 1:100,000 scale DLG, and 1:24,000 scale hydrography lines....

  17. Dual boundary spanning

    DEFF Research Database (Denmark)

    Li-Ying, Jason

    2016-01-01

    The extant literature runs short in understanding openness of innovation regarding and the different pathways along which internal and external knowledge resources can be combined. This study proposes a unique typology for outside-in innovations based on two distinct ways of boundary spanning: wh...

  18. Boundaries of the universe

    CERN Document Server

    Glasby, John S

    2013-01-01

    The boundaries of space exploration are being pushed back constantly, but the realm of the partially understood and the totally unknown is as great as ever. Among other things this book deals with astronomical instruments and their application, recent discoveries in the solar system, stellar evolution, the exploding starts, the galaxies, quasars, pulsars, the possibilities of extraterrestrial life and relativity.

  19. Minnesota County Boundaries - lines

    Data.gov (United States)

    Minnesota Department of Natural Resources — Minnesota county boundaries derived from a combination of 1:24,000 scale PLS lines, 1:100,000 scale TIGER, 1:100,000 scale DLG, and 1:24,000 scale hydrography lines....

  20. Transport, boundary physics

    International Nuclear Information System (INIS)

    Romanelli, F.

    2001-01-01

    In this paper the contributions presented at the 18 th IAEA Fusion Energy Conference in the field of transport and boundary physics will be summarised with reference to the following distinct issues: H-mode physics, Internal Transport Barrier formation, transport studies, Radiative Improved modes and impurity seeding, divertor and He exhaust, new configurations. (author)

  1. Targeting Polycomb to Pericentric Heterochromatin in Embryonic Stem Cells Reveals a Role for H2AK119u1 in PRC2 Recruitment

    Directory of Open Access Journals (Sweden)

    Sarah Cooper

    2014-06-01

    Full Text Available The mechanisms by which the major Polycomb group (PcG complexes PRC1 and PRC2 are recruited to target sites in vertebrate cells are not well understood. Building on recent studies that determined a reciprocal relationship between DNA methylation and Polycomb activity, we demonstrate that, in methylation-deficient embryonic stem cells (ESCs, CpG density combined with antagonistic effects of H3K9me3 and H3K36me3 redirects PcG complexes to pericentric heterochromatin and gene-rich domains. Surprisingly, we find that PRC1-linked H2A monoubiquitylation is sufficient to recruit PRC2 to chromatin in vivo, suggesting a mechanism through which recognition of unmethylated CpG determines the localization of both PRC1 and PRC2 at canonical and atypical target sites. We discuss our data in light of emerging evidence suggesting that PcG recruitment is a default state at licensed chromatin sites, mediated by interplay between CpG hypomethylation and counteracting H3 tail modifications.

  2. Grain Boundary Segregation in Metals

    CERN Document Server

    Lejcek, Pavel

    2010-01-01

    Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.

  3. Adaptive Sentence Boundary Disambiguation

    OpenAIRE

    Palmer, David D.; Hearst, Marti A.

    1994-01-01

    Labeling of sentence boundaries is a necessary prerequisite for many natural language processing tasks, including part-of-speech tagging and sentence alignment. End-of-sentence punctuation marks are ambiguous; to disambiguate them most systems use brittle, special-purpose regular expression grammars and exception rules. As an alternative, we have developed an efficient, trainable algorithm that uses a lexicon with part-of-speech probabilities and a feed-forward neural network. After training ...

  4. Boundary-layer theory

    CERN Document Server

    Schlichting (Deceased), Hermann

    2017-01-01

    This new edition of the near-legendary textbook by Schlichting and revised by Gersten presents a comprehensive overview of boundary-layer theory and its application to all areas of fluid mechanics, with particular emphasis on the flow past bodies (e.g. aircraft aerodynamics). The new edition features an updated reference list and over 100 additional changes throughout the book, reflecting the latest advances on the subject.

  5. Cell boundary fault detection system

    Science.gov (United States)

    Archer, Charles Jens [Rochester, MN; Pinnow, Kurt Walter [Rochester, MN; Ratterman, Joseph D [Rochester, MN; Smith, Brian Edward [Rochester, MN

    2009-05-05

    A method determines a nodal fault along the boundary, or face, of a computing cell. Nodes on adjacent cell boundaries communicate with each other, and the communications are analyzed to determine if a node or connection is faulty.

  6. Numerical methods for hypersonic boundary layer stability

    Science.gov (United States)

    Malik, M. R.

    1990-01-01

    Four different schemes for solving compressible boundary layer stability equations are developed and compared, considering both the temporal and spatial stability for a global eigenvalue spectrum and a local eigenvalue search. The discretizations considered encompass: (1) a second-order-staggered finite-difference scheme; (2) a fourth-order accurate, two-point compact scheme; (3) a single-domain Chebychev spectral collocation scheme; and (4) a multidomain spectral collocation scheme. As Mach number increases, the performance of the single-domain collocation scheme deteriorates due to the outward movement of the critical layer; a multidomain spectral method is accordingly designed to furnish superior resolution of the critical layer.

  7. Boundaries and Boundary Marks - Substantive Cultural Heritage of Extensive Importance

    Science.gov (United States)

    Waldhaeusl, P.; Koenig, H.; Mansberger, R.

    2015-08-01

    The Austrian Society for surveying and Geoinformation (ASG) has proposed to submit "Boundaries and Boundary Marks" for the UNESCO World Heritage title. It was time that boundaries, borders and limits of all types as well as ownership rights would find the proper attention in the global public. Landmarks symbolize the real property and the associated rights and obligations, in a figurative sense, the property generally and all legal limits. A democratic state of law is impossible at today's population density without a functioning land administration system with surveying and jurisdiction. As monumental World Heritage representatives of the geodetic artwork "Boundaries and Boundary Marks" are specifically proposed: remaining monuments of the original cadastral geodetic network, the first pan-Austrian surveying headquarters in Vienna, and a specific selection of outstanding boundary monuments. Landmarks are monuments to the boundaries which separate rights and obligations, but also connect the neighbors peacefully after written agreement. "And cursed be he who does not respect the boundaries" you wrote already 3000 years ago. Boundaries and Boundary Marks are a real thing; they all belong to the tangible or material heritage of human history. In this context also the intangible heritage is discussed. This refers to oral tradition and expressions, performing arts; social practices, rituals and festive events; as well as to knowledge and practices handling nature and the universe. "Boundaries and Boundary Marks" do not belong to it, but clearly to the material cultural world heritage. "Boundary and Boundary Marks" is proposed to be listed according to the criteria (ii),(iv),(vi).

  8. An Optical Study of Ice Grain Boundaries

    Science.gov (United States)

    Thomson, Erik S.

    The equilibrium phase geometry and evolution of polycrystals underlies the nature of materials. In particular, grain boundaries dominate the total interfacial area within polycrystalline materials. Our experimental studies are motivated by the importance of the structure, evolution, and thermodynamic behavior of grain boundaries near bulk melting temperatures. Ice is singled out as a material of interest due to its geophysical importance and its advantageous optical properties. An experimental apparatus and light reflection technique is designed to measure grain boundary melting in ice bicrystals, in thermodynamic equilibrium The technique allows continuous monitoring of reflected light intensity from the grain boundary as the temperature and solutal composition are systematically varied. For each sample the individual crystal orientations are also measured. The type and concentration of impurity in the liquid is controlled and the temperature is continuously recorded and controlled over a range near the melting point. An optical model of the interface is developed in order to convert experimental reflection data into a physical measurement of the liquidity of the grain boundary. Solutions are found for reflection and transmission amplitude coefficients for waves propagating from an arbitrarily oriented uniaxial anisotropic material into an isotropic material. This general model is used to determine solutions for three layer, ice/water/ice, systems with crystals of arbitrary orientation, and is broadly applicable to layered materials. Experimental results show thicker grain boundary liquid layers than expected from classical colligative effects. A physically realistic model of intermolecular interactions succeeds in bounding the measurements. These measurements may have important implications for understanding a wide range of effects in polycrystalline materials. Likewise, the experimental techniques and optical theory may be applied to other systems of broad

  9. Anisotropy across Superplume Boundaries

    Science.gov (United States)

    Cottaar, S.; Romanowicz, B. A.

    2011-12-01

    Sdiff data sets are presented for paths that run parallel to the African and the Pacific superplume boundaries. Objective clustering of waveforms illustrates sharp changes across these boundaries. The African plume shows a sharp offset in travel times in the SHdiff phase, while a more gradual offset towards slower arrivals is seen in the case of the Pacific superplume. Additionally, Pdiff phases display no offset around the African plume and a weak one around the Pacific plume. Here we focus mainly on another striking feature observed in both cases: outside of the superplume the Sdiff particle motion is strongly elliptical, but becomes linear within the superplume (first noticed by To et al. 2005 in the African superplume case). For the African plume we argue that these observations of delayed SV at large distances (~120 degrees) are indicative of the occurrence of azimuthal anisotropy. The SV arrivals have similar polarity as SH, opposite from what their radiation pattern predicts. Azimuthal anisotropy causes SH energy to be converted to SV (Maupin, 1994), explaining the travel time, polarity and amplitude. Forward modeling through different isotropic and anisotropic models supports this statement, although there are trade-offs between direction and magnitude of azimuthal anisotropy. The strong elliptical particle motions are also observed outside the Pacific plume, but at shorter distances (95-105 degrees). Elliptical motions can occur in the absence of anisotropy when strong velocity deviations or layering occurs close to the CMB, which, based on velocity profiles with depth in global tomographic models would be more likely within the superplume rather than on the fast side. The elliptical particle motions here can be modelled with a simple transverse isotropic model with VSH>VSV, but azimuthal anisotropy cannot be ruled out. The complexities within the Pacific superplume, including strong amplitude drop and existence of a post-cursor, are likely caused by an

  10. The Arabidopsis GAGA-Binding Factor BASIC PENTACYSTEINE6 Recruits the POLYCOMB-REPRESSIVE COMPLEX1 Component LIKE HETEROCHROMATIN PROTEIN1 to GAGA DNA Motifs.

    Science.gov (United States)

    Hecker, Andreas; Brand, Luise H; Peter, Sébastien; Simoncello, Nathalie; Kilian, Joachim; Harter, Klaus; Gaudin, Valérie; Wanke, Dierk

    2015-07-01

    Polycomb-repressive complexes (PRCs) play key roles in development by repressing a large number of genes involved in various functions. Much, however, remains to be discovered about PRC-silencing mechanisms as well as their targeting to specific genomic regions. Besides other mechanisms, GAGA-binding factors in animals can guide PRC members in a sequence-specific manner to Polycomb-responsive DNA elements. Here, we show that the Arabidopsis (Arabidopsis thaliana) GAGA-motif binding factor protein basic pentacysteine6 (BPC6) interacts with like heterochromatin protein1 (LHP1), a PRC1 component, and associates with vernalization2 (VRN2), a PRC2 component, in vivo. By using a modified DNA-protein interaction enzyme-linked immunosorbant assay, we could show that BPC6 was required and sufficient to recruit LHP1 to GAGA motif-containing DNA probes in vitro. We also found that LHP1 interacts with VRN2 and, therefore, can function as a possible scaffold between BPC6 and VRN2. The lhp1-4 bpc4 bpc6 triple mutant displayed a pleiotropic phenotype, extreme dwarfism and early flowering, which disclosed synergistic functions of LHP1 and group II plant BPC members. Transcriptome analyses supported this synergy and suggested a possible function in the concerted repression of homeotic genes, probably through histone H3 lysine-27 trimethylation. Hence, our findings suggest striking similarities between animal and plant GAGA-binding factors in the recruitment of PRC1 and PRC2 components to Polycomb-responsive DNA element-like GAGA motifs, which must have evolved through convergent evolution. © 2015 American Society of Plant Biologists. All Rights Reserved.

  11. Seven New Complete Plastome Sequences Reveal Rampant Independent Loss of the ndh Gene Family across Orchids and Associated Instability of the Inverted Repeat/Small Single-Copy Region Boundaries.

    Directory of Open Access Journals (Sweden)

    Hyoung Tae Kim

    Full Text Available Earlier research has revealed that the ndh loci have been pseudogenized, truncated, or deleted from most orchid plastomes sequenced to date, including in all available plastomes of the two most species-rich subfamilies, Orchidoideae and Epidendroideae. This study sought to resolve deeper-level phylogenetic relationships among major orchid groups and to refine the history of gene loss in the ndh loci across orchids. The complete plastomes of seven orchids, Oncidium sphacelatum (Epidendroideae, Masdevallia coccinea (Epidendroideae, Sobralia callosa (Epidendroideae, Sobralia aff. bouchei (Epidendroideae, Elleanthus sodiroi (Epidendroideae, Paphiopedilum armeniacum (Cypripedioideae, and Phragmipedium longifolium (Cypripedioideae were sequenced and analyzed in conjunction with all other available orchid and monocot plastomes. Most ndh loci were found to be pseudogenized or lost in Oncidium, Paphiopedilum and Phragmipedium, but surprisingly, all ndh loci were found to retain full, intact reading frames in Sobralia, Elleanthus and Masdevallia. Character mapping suggests that the ndh genes were present in the common ancestor of orchids but have experienced independent, significant losses at least eight times across four subfamilies. In addition, ndhF gene loss was correlated with shifts in the position of the junction of the inverted repeat (IR and small single-copy (SSC regions. The Orchidaceae have unprecedented levels of homoplasy in ndh gene presence/absence, which may be correlated in part with the unusual life history of orchids. These results also suggest that ndhF plays a role in IR/SSC junction stability.

  12. Seven New Complete Plastome Sequences Reveal Rampant Independent Loss of the ndh Gene Family across Orchids and Associated Instability of the Inverted Repeat/Small Single-Copy Region Boundaries.

    Science.gov (United States)

    Kim, Hyoung Tae; Kim, Jung Sung; Moore, Michael J; Neubig, Kurt M; Williams, Norris H; Whitten, W Mark; Kim, Joo-Hwan

    2015-01-01

    Earlier research has revealed that the ndh loci have been pseudogenized, truncated, or deleted from most orchid plastomes sequenced to date, including in all available plastomes of the two most species-rich subfamilies, Orchidoideae and Epidendroideae. This study sought to resolve deeper-level phylogenetic relationships among major orchid groups and to refine the history of gene loss in the ndh loci across orchids. The complete plastomes of seven orchids, Oncidium sphacelatum (Epidendroideae), Masdevallia coccinea (Epidendroideae), Sobralia callosa (Epidendroideae), Sobralia aff. bouchei (Epidendroideae), Elleanthus sodiroi (Epidendroideae), Paphiopedilum armeniacum (Cypripedioideae), and Phragmipedium longifolium (Cypripedioideae) were sequenced and analyzed in conjunction with all other available orchid and monocot plastomes. Most ndh loci were found to be pseudogenized or lost in Oncidium, Paphiopedilum and Phragmipedium, but surprisingly, all ndh loci were found to retain full, intact reading frames in Sobralia, Elleanthus and Masdevallia. Character mapping suggests that the ndh genes were present in the common ancestor of orchids but have experienced independent, significant losses at least eight times across four subfamilies. In addition, ndhF gene loss was correlated with shifts in the position of the junction of the inverted repeat (IR) and small single-copy (SSC) regions. The Orchidaceae have unprecedented levels of homoplasy in ndh gene presence/absence, which may be correlated in part with the unusual life history of orchids. These results also suggest that ndhF plays a role in IR/SSC junction stability.

  13. Shared care and boundaries:

    DEFF Research Database (Denmark)

    Winthereik, Brit Ross

    2008-01-01

    Purpose – The paper seeks to examine how an online maternity record involving pregnant women worked as a means to create shared maternity care. Design/methodology/approach – Ethnographic techniques have been used. The paper adopts a theoretical/methodological framework based on science and techno......Purpose – The paper seeks to examine how an online maternity record involving pregnant women worked as a means to create shared maternity care. Design/methodology/approach – Ethnographic techniques have been used. The paper adopts a theoretical/methodological framework based on science...... and technology studies. Findings – The paper shows how a version of “the responsible patient” emerges from the project which is different from the version envisioned by the project organisation. The emerging one is concerned with the boundary between primary and secondary sector care, and not with the boundary...... of responsibilities entailed in shared care projects. Rather than seeking to connect all actors in an unbounded space, shared care might instead suggest a space for patients and professionals to experiment with new roles and responsibilities. Practical implications – When designing coordination tools for health care...

  14. Destiny of earthward streaming plasma in the plasmasheet boundary layer

    Science.gov (United States)

    Green, J. L.; Horwitz, J. L.

    1986-01-01

    The dynamics of the earth's magnetotail have been investigated, and it has become clear that the plasmasheet boundary layer field lines map into the Region I Field-Aligned Currents (FAC) of the auroral zone. It is pointed out that the role of earthward streaming ions in the plasmasheet boundary layer may be of fundamental importance in the understanding of magnetotail dynamics, auroral zone physics, and especially for ionospheric-magnetospheric interactions. The present paper has the objective to evaluate propagation characteristics for the earthward streaming ions observed in the plasmasheet boundary layer. An investigation is conducted of the propagation characteristics of protons in the plasmasheet boundary layer using independent single particle dynamics, and conclusions are discussed. The density of earthward streaming ions found in the plasmasheet boundary layer should include the ring current as well as the auroral zone precipitaiton and inner plasmasheet regions of the magnetosphere.

  15. Collaboration in Healthcare Through Boundary Work and Boundary Objects

    DEFF Research Database (Denmark)

    Meier, Ninna

    2015-01-01

    . In highly specialized, knowledge-intensive organizations such as healthcare organizations, organizational, professional, and disciplinary boundaries mark the formal structure and division of work. Collaboration and coordination across these boundaries are essential to minimizing gaps in patient care......, but also may be challenging to achieve in practice. By drawing on data from an ethnographic study of two hospital wards, this article investigates practices of cross-disciplinary and professional collaboration and adds to our knowledge of how this kind of boundary work is produced in context. Moreover......, it adds to existing boundary literature by exploring the fast-paced, situational, micro-interactions in which boundaries are drawn, maintained, and dissolved. These mundane, brief exchanges are essential to the practice of collaboration through boundary work. I consider the implications of these findings...

  16. Boundary work for implementing adaptive management: A water sector application.

    Science.gov (United States)

    Adem Esmail, Blal; Geneletti, Davide; Albert, Christian

    2017-09-01

    Boundary work, defined as effort to mediate between knowledge and action, is a promising approach for facilitating knowledge co-production for sustainable development. Here, we investigate a case study of knowledge co-production, to assess the applicability of boundary work as a conceptual framework to support implementing adaptive management in the water sector. We refer to a boundary work classification recently proposed by Clark et al., (2016), based on three types of knowledge uses, i.e. enlightenment, decision-, and negotiation-support, and three types of sources, i.e. personal expertise, single, and multiple communities of expertise. Our empirical results confirm boundary work has been crucial for the three types of knowledge use. For enlightenment and decision-support, effective interaction among knowledge producers and users was achieved through diverse boundary work practices, including joint agenda setting, and sharing of data and expertise. This initial boundary work eased subsequent knowledge co-production for decision-support and negotiations, in combination with stepping up of cooperation between relevant actors, suitable legislation and pressure for problem solving. Our analysis highlighted the temporal dimension matters - building trust around enlightenment first, and then using this as a basis for managing knowledge co-production for decision-, and negotiation support. We reconfirmed that boundary work is not a single time achievement, rather is a dynamic process, and we emphasized the importance of key actors driving the process, such as water utilities. Our results provide a rich case study of how strategic boundary work can facilitate knowledge co-production for adaptive management in the water sector. The boundary work practices employed here could also be transferred to other cases. Water utilities, as intermediaries between providers and beneficiaries of the important water-related ecosystem service of clean water provision, can indeed serve

  17. Challenging the Boundaries

    DEFF Research Database (Denmark)

    Nørgaard, Nina

    2004-01-01

    to explore in the study and teaching of foreign languages. Not only may linguistics and literature be employed to shed light on each other, the insights gained may furthermore prove useful in a broader context in our foreign language studies. The article begins with a brief introduction to literary...... linguistics in general and to Hallidayan linguistics in particular. The theoretical framework thus laid out, it is exemplified how Halliday's theory of language may be employed in the analysis of literature. The article concludes by considering the possible status of literary linguistics in a broader......To many people, challenging the boundaries between the traditional disciplines in foreign language studies means doing cultural studies. The aim of this article is to pull in a different direction by suggesting how the interface between linguistics and literature may be another fertile field...

  18. Negotiating Cluster Boundaries

    DEFF Research Database (Denmark)

    Giacomin, Valeria

    2017-01-01

    Palm oil was introduced to Malay(si)a as an alternative to natural rubber, inheriting its cluster organizational structure. In the late 1960s, Malaysia became the world’s largest palm oil exporter. Based on archival material from British colonial institutions and agency houses, this paper focuses...... on the governance dynamics that drove institutional change within this cluster during decolonization. The analysis presents three main findings: (i) cluster boundaries are defined by continuous tug-of-war style negotiations between public and private actors; (ii) this interaction produces institutional change...... within the cluster, in the form of cumulative ‘institutional rounds’ – the correction or disruption of existing institutions or the creation of new ones; and (iii) this process leads to a broader inclusion of local actors in the original cluster configuration. The paper challenges the prevalent argument...

  19. Origin of Boundary Populations in Medaka (Oryzias latipes Species Complex).

    Science.gov (United States)

    Takehana, Yusuke; Sakai, Masato; Narita, Takanori; Sato, Tadashi; Naruse, Kiyoshi; Sakaizumi, Mitsuru

    2016-04-01

    The Japanese wild population of the medaka fish (Oryzias latipes species complex) comprises two genetically distinct groups, the Northern and the Southern Populations, with boundary populations having a unique genotype. It is thought that the boundary populations have been formed through introgressive hybridization between the two groups, because they are fixed with the Northern alleles at two allozymic loci, with the Southern alleles at two other loci, and have a unique allele at one locus. In this study, we examined the genetic population structure of the boundary populations using genome-wide single nucleotide polymorphism (SNP) data. Most SNPs of the Toyooka population, a typical boundary population, were shared with the Northern Population, some were shared with the Southern Population, and the remaining SNPs were unique to this population, suggesting that the boundary populations originated and diverged from the Northern Population. Further analyses of different populations using SNPs at eight genomic loci indicated that the boundary populations at different locations share similar genomic constitutions, and can be genetically distinguished from typical Northern Populations by unique SNPs. In addition, the boundary populations in the Maruyama River Basin had Northern mitochondrial DNA (mtDNA), while others, from the Fukuda and Kishida River Basins and from the Kumihama Bay area, had Southern mtDNA. These findings suggested that the boundary populations originated from the Northern Population, and then their genomes diverged as a result of geographical isolation, followed by mtDNA introgression from the Southern Population that occurred independently in some populations.

  20. Grain boundary melting in ice

    OpenAIRE

    Thomson, E. S.; Hansen-Goos, Hendrik; Wilen, L. A.; Wettlaufer, J. S.

    2012-01-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentr...

  1. Conformal boundaries of warped products

    DEFF Research Database (Denmark)

    Kokkendorff, Simon Lyngby

    2006-01-01

    In this note we prove a result on how to determine the conformal boundary of a type of warped product of two length spaces in terms of the individual conformal boundaries. In the situation, that we treat, the warping and conformal distortion functions are functions of distance to a base point....... The result is applied to produce examples of CAT(0)-spaces, where the conformal and ideal boundaries differ in interesting ways....

  2. Boundary Spanners in Global Partnerships

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    2017-01-01

    managers’ boundary-spanning activities and a context-sensitive understanding of their boundary work. The study applies Bourdieu’s concept of capital (economic, cultural, social, and symbolic) not only in its analysis of the two powerful partners but also in its discussion of the boundary......-spanning activities that are reported. The analysis demonstrates the coexistence of transactive and transformative modes of collaboration in the studied case. It reveals both the importance of partner status and the impact of that status on the forms of boundary-spanning activities in which the partners engage...

  3. Analysis of turbulent boundary layers

    CERN Document Server

    Cebeci, Tuncer

    1974-01-01

    Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculati

  4. Allegheny County Watershed Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the 52 isolated sub-Watersheds of Allegheny County that drain to single point on the main stem rivers. Created by 3 Rivers 2nd Nature based...

  5. Boundary-Layer & health

    Science.gov (United States)

    Costigliola, V.

    2010-09-01

    It has long been known that specific atmospheric processes, such as weather and longer-term climatic fluctuations, affect human health. The biometeorological literature refers to this relationship as meteorotropism, defined as a change in an organism that is correlated with a change in atmospheric conditions. Plenty of (patho)physiological functions are affected by those conditions - like the respiratory diseases - and currently it is difficult to put any limits for pathologies developed in reply. Nowadays the importance of atmospheric boundary layer and health is increasingly recognised. A number of epidemiologic studies have reported associations between ambient concentrations of air pollution, specifically particulate pollution, and adverse health effects, even at the relatively low concentrations of pollution found. Since 1995 there have been over twenty-one studies from four continents that have explicitly examined the association between ambient air pollutant mixes and daily mortality. Statistically significant and positive associations have been reported in data from various locations around the world, all with varying air pollutant concentrations, weather conditions, population characteristics and public health policies. Particular role has been given to atmospheric boundary layer processes, the impact of which for specific patient-cohort is, however, not well understood till now. Assessing and monitoring air quality are thus fundamental to improve Europe's welfare. One of current projects run by the "European Medical Association" - PASODOBLE will develop and demonstrate user-driven downstream information services for the regional and local air quality sectors by combining space-based and in-situ data with models in 4 thematic service lines: - Health community support for hospitals, pharmacies, doctors and people at risk - Public information for regions, cities, tourist industry and sporting event organizers - Compliance monitoring support on particulate

  6. Heterochromatin polymorphism and physical mapping of 5S and 18S ribosomal DNA in four populations of Hypostomus strigaticeps (Regan, 1907) from the Paraná River basin, Brazil: evolutionary and environmental correlation.

    Science.gov (United States)

    Baumgärtner, Lucas; Paiz, Leonardo Marcel; Zawadzki, Cláudio Henrique; Margarido, Vladimir Pavan; Castro, Ana Luiza de Brito Portela

    2014-10-01

    A cytogenetic analysis was performed on four populations of Hypostomus strigaticeps from the Paraná River basin, Brazil. Two populations were collected from the large channel river at the Itaipu reservoir area and the other two were from the upper stretches of tributaries of the Paraná River. All populations showed 2n=72 chromosomes (12m+12sm+18st+30a), intra- and interpopulation 18S rDNA site polymorphisms (two to three acrocentric chromosome pairs), and multiple 5S rDNA sites in three chromosome pairs (4, 21, and 28). C-banding revealed heterochromatin located in the centromere and pericentromere regions of most chromosome; however, large heterochromatic blocks (CMA3(-)/DAPI(+)) on the long arm of acrocentric chromosomes identified intra- and interpopulation polymorphism. The amount and distribution of heterochromatin seem to be correlated to biogeographical characteristics of H. strigaticeps along the Paraná River. Morphometric results also showed diversity among the populations, suggesting phenotypic plasticity of this species. Evolutionary, taxonomy, and biogeographical approaches with regard to H. strigaticeps and interrelationships in Hypostomus are discussed.

  7. Contraction and elongation: Mechanics underlying cell boundary deformations in epithelial tissue.

    Science.gov (United States)

    Hara, Yusuke

    2017-06-01

    The cell-cell boundaries of epithelial cells form cellular frameworks at the apical side of tissues. Deformations in these boundaries, for example, boundary contraction and elongation, and the associated forces form the mechanical basis of epithelial tissue morphogenesis. In this review, using data from recent Drosophila studies on cell boundary contraction and elongation, I provide an overview of the mechanism underlying the bi-directional deformations in the epithelial cell boundary, that are sustained by biased accumulations of junctional and apico-medial non-muscle myosin II. Moreover, how the junctional tensions exist on cell boundaries in different boundary dynamics and morphologies are discussed. Finally, some future perspectives on how recent knowledge about single cell boundary-level mechanics will contribute to our understanding of epithelial tissue morphogenesis are discussed. © 2017 Japanese Society of Developmental Biologists.

  8. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    transfer between two major faults, and parallel to the geothermal area extension. 1. Introduction. Plate boundaries are the zones where most earth dynamics are focussed. The complexity of tectonic boundaries draws attention to them as the largest earthquakes are felt in these areas and they elicit the natural hazard of ...

  9. Nucleation of small angle boundaries

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1996-12-01

    Full Text Available The internal stresses induced by the strain gradients in an array of lattice cells delineated by low-angle dislocation boundaries are partially relieved by the creation of new low-angle boundaries. This is shown to be a first-order transition...

  10. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    time series to determine the causality and related orientation. The resulting link orientations at the plate boundary conditions indicate that causal triggering seems to be localized along a major fault, as a stress transfer between two major faults, and parallel to the geothermal area extension. 1. Introduction. Plate boundaries ...

  11. Effect of cloud boundaries on reflected radiation

    Science.gov (United States)

    Coakley, James A., Jr.

    1990-01-01

    The effects of cloud boundaries on cloud reflectivity are evaluated by comparing satellite-observed reflectivities for layered clouds that are uniform over scales that are large compared with the field of view of the satellite radiometer and those of the same clouds where they are broken on scales which are small compared with the field of view. Results are given for 1 km AVHRR data. The reflectivities are compared at 0.63 micron for which droplets in stratiform water clouds are nonabsorbing, and at 3.7 microns where the single-scattering albedo of the droplets is typically about 0.9 micron.

  12. Boundary dynamics in dilaton gravity

    International Nuclear Information System (INIS)

    Das, S.R.; Mukherji, S.

    1994-06-01

    We study the dynamics of the boundary in two dimensional dilaton gravity coupled to N massless scalars. We rederive the boundary conditions of [1] and [3] in a way which makes the requirement of reparametrization invariance and the role of conformal anomaly explicit. We then study the semiclassical behaviour of the boundary in the N=24 theory in the presence of an incoming matter wave with a constant energy flux spread over a finite interval. There is a critical value of the matter energy density below which the boundary is stable and all the matter is reflected back. For energy densities greater than this critical value there is a similar behaviour for small values of the total energy thrown in. However, when the total energy exceeds another critical value the boundary exhibits a runaway behaviour and the spacetime develops in singularities and horizons. (author). 10 refs, 3 figs

  13. Boundary Drawing in Clinical Work

    DEFF Research Database (Denmark)

    Meier, Ninna

    The aim of this paper is to show how health care professionals temporarily dissolve and redraw boundaries in their everyday work, in order to coordinate clinical work and facilitate collaboration in patient pathways. Boundaries are social constructions that help us make sense of our complex, social...... world. In health care, formal boundaries are important distinctions that separate health care practitioners into medical specialties, professions and organizational departments. But clinical work also relies on the ability of health care practitioners to collaborate around patients in formal...... arrangements or emergent, temporary teams. Focusing on the cognitive and social boundaries we draw to establish identity and connection (to a profession, team or person) the paper shows how health care professionals can use inter-personal relationships to temporarily dismiss formal boundaries. By redrawing...

  14. Boundary operators in effective string theory

    Energy Technology Data Exchange (ETDEWEB)

    Hellerman, Simeon [Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo,Kashiwa, Chiba 277-8582 (Japan); Swanson, Ian [Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo,Kashiwa, Chiba 277-8582 (Japan)

    2017-04-13

    Various universal features of relativistic rotating strings depend on the organization of allowed local operators on the worldsheet. In this paper, we study the set of Neumann boundary operators in effective string theory, which are relevant for the controlled study of open relativistic strings with freely moving endpoints. Relativistic open strings are thought to encode the dynamics of confined quark-antiquark pairs in gauge theories in the planar approximation. Neumann boundary operators can be organized by their behavior under scaling of the target space coordinates X{sup μ}, and the set of allowed X-scaling exponents is bounded above by +1/2 and unbounded below. Negative contributions to X-scalings come from powers of a single invariant, or “dressing' operator, which is bilinear in the embedding coordinates. In particular, we show that all Neumann boundary operators are dressed by quarter-integer powers of this invariant, and we demonstrate how this rule arises from various ways of regulating the short-distance singularities of the effective theory.

  15. Studying alumina boundary migration using combined microscopy techniques

    International Nuclear Information System (INIS)

    Riesterer, J L; Farrer, J K; Munoz, N E; Gilliss, S R; Ravishankar, N; Carter, C B

    2006-01-01

    Thermal grooving and migration of grain boundaries in alumina have been investigated using a variety of microscopy techniques. Using two different methods, polycrystalline alumina was used to investigate wet (implying the presence of a glassy phase), and dry grain boundaries. In the first, single-crystal Al 2 O 3 was hot-pressed via liquid phase sintering (LPS) to polycrystalline alumina with an anorthite glass film at the interface. Pulsed laser deposition was used to deposit approximately 100-nm thick glass films. Specimens were annealed in air at 1650 deg. C for 20 h to induce boundary migration. Boundary characterization was carried out using visible light (VLM) and scanning electron (SEM) microscopies. Effects on migration due to surface orientation of grains were investigated using electron backscatter diffraction (EBSD). The second method dealt with heat treating dry boundaries in polycrystalline alumina to monitor boundary migration behavior via remnant thermal grooves. Heat treatments were conducted at 1650 deg. C for 30 min. The same region of the sample was mapped using VLM and atomic force microscopy (AFM) and followed over a series of 30 min heat treatments. Boundary migration through a pore trapped inside the grain matrix was of particular interest

  16. Studying alumina boundary migration using combined microscopy techniques

    Energy Technology Data Exchange (ETDEWEB)

    Riesterer, J L [Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Ave, SE., Minneapolis, MN 55455 (United States); Farrer, J K [Now at Physics and Astronomy, Brigham Young University, Provo, UT 84602 (United States); Munoz, N E [Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Ave, SE., Minneapolis, MN 55455 (United States); Gilliss, S R [Now at Robins, Kaplan, Miller and Ciresi, L.L.P., Minneapolis, MN 55402 (United States); Ravishankar, N [Now at Materials Research Centre, Indian Institute of Science, Bangalore, 560 012 (India); Carter, C B [Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Ave, SE., Minneapolis, MN 55455 (United States)

    2006-02-22

    Thermal grooving and migration of grain boundaries in alumina have been investigated using a variety of microscopy techniques. Using two different methods, polycrystalline alumina was used to investigate wet (implying the presence of a glassy phase), and dry grain boundaries. In the first, single-crystal Al{sub 2}O{sub 3} was hot-pressed via liquid phase sintering (LPS) to polycrystalline alumina with an anorthite glass film at the interface. Pulsed laser deposition was used to deposit approximately 100-nm thick glass films. Specimens were annealed in air at 1650 deg. C for 20 h to induce boundary migration. Boundary characterization was carried out using visible light (VLM) and scanning electron (SEM) microscopies. Effects on migration due to surface orientation of grains were investigated using electron backscatter diffraction (EBSD). The second method dealt with heat treating dry boundaries in polycrystalline alumina to monitor boundary migration behavior via remnant thermal grooves. Heat treatments were conducted at 1650 deg. C for 30 min. The same region of the sample was mapped using VLM and atomic force microscopy (AFM) and followed over a series of 30 min heat treatments. Boundary migration through a pore trapped inside the grain matrix was of particular interest.

  17. Grain-boundary migration in Zr-Sn alloys

    International Nuclear Information System (INIS)

    Snowden, K.U.; Stathers, P.A.; Hughes, D.S.

    1979-01-01

    Measurements are reported of grain-boundary migration in a series of Zr-Sn alloys containing from 0.75 to 5.1 wt% Sn (0.58 to 4.0 at% Sn) fatigued under vacuum at temperatures between 600 and 775 0 C. At these temperatures, the condition of the alloys correspond to either the single phase (α) or the double phase (α + Zr 4 Sn) regions of the phase diagram. The amount and rate of grain-boundary migration increased with temperature and decreased with tin addition. The dependence of grain-boundary migration on tin content was a minimum at tin compositions which corresponded to the reported region of the α/(α + Zr 4 Sn) boundary. In the α-region, the reciprocal of the rate of grain-boundary migration was approximately linear with tin content. The temperature dependence for grain-boundary migration exhibited a kinetic transition temperature which divided the dependence into two ranges characterised by different apparent activation energies. The effect of tin additions on both activation energies was to first reduce and then to increase their value. This latter increase is possibly associated with the precipitation of Zr 4 Sn at grain boundaries. (orig.)

  18. Basic aspects of high-Tc grain boundary devices

    International Nuclear Information System (INIS)

    Mannhart, J.; Moler, K.A.; Sigrist, M.

    1996-01-01

    Grain boundaries are extensively used as high-quality Josephson junctions in high-T c superconductors. Their superconducting characteristics can generally be well described by conventional models of strongly coupled Josephson junctions. Here, we report on highly anomalous critical current vs. magnetic field dependencies of grain boundaries in YBa 2 Cu 3 O 7-x . Direct imaging with scanning SQUID microscopy provides evidence of magnetic flux generated by single grain boundaries. Conventional Josephson junction models cannot explain these effects if a superconducting order parameter with a pure s-wave symmetry is assumed. The results have significant implications for our understanding of the properties of grain boundaries in high-T c superconductors and for their applications. (orig.)

  19. Wave boundary layer hydrodynamics during onshore bar migration

    NARCIS (Netherlands)

    Henriquez, M.; Reniers, A.; Ruessink, G.; Stive, M.J.F.

    2010-01-01

    To study onshore bar migration and the accompanying intra-wave sediment transport a wave flume experiment was conducted. The wave flume had a rigid bottom with a single bar profile. The focus of the experiment was to measure the hydrodynamics in the wave bottom boundary layer. The results show that

  20. Grain boundary melting in ice

    Science.gov (United States)

    Thomson, E. S.; Hansen-Goos, Hendrik; Wettlaufer, J. S.; Wilen, L. A.

    2013-03-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentration. Although we understand that the interfacial surface charge densities qs and solute concentrations can potentially dominate the film thickness, we cannot directly measure them within a given grain boundary. Therefore, as a framework for interpreting the data we consider two appropriate qs dependent limits; one is dominated by the colligative effect and other is dominated by electrostatic interactions.

  1. Allegheny County School District Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the school district boundaries within Allegheny County If viewing this description on the Western Pennsylvania Regional Data Center’s open...

  2. County Boundaries with Shorelines (National)

    Data.gov (United States)

    Department of Transportation — County boundaries with shorelines cut in (NTAD). The TIGER/Line Files are shapefiles and related database files (.dbf) that are an extract of selected geographic and...

  3. State Highway District Boundaries - 2004

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This data represents the NM Department of Transportation District boundaries as legislatively defined (i.e. these are not maintenance defined districts).

  4. HUC 8-11 Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This data set is a digital hydrologic unit boundary that is at the 4-digit, 6-digit, 8-digit, and 11-digit level. The data set was developed by delineating the...

  5. Analytic invariants of boundary links

    OpenAIRE

    Garoufalidis, Stavros; Levine, Jerome

    2001-01-01

    Using basic topology and linear algebra, we define a plethora of invariants of boundary links whose values are power series with noncommuting variables. These turn out to be useful and elementary reformulations of an invariant originally defined by M. Farber.

  6. The laminar boundary layer equations

    CERN Document Server

    Curle, N

    2017-01-01

    Thorough introduction to boundary layer problems offers an ordered, logical presentation accessible to undergraduates. The text's careful expositions of the limitations and accuracy of various methods will also benefit professionals. 1962 edition.

  7. Allegheny County Zip Code Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the zip code boundaries that lie within Allegheny County.If viewing this description on the Western Pennsylvania Regional Data Center’s open...

  8. Recognition of boundary feedback systems

    DEFF Research Database (Denmark)

    Pedersen, Michael

    1989-01-01

    A system that has been the object of intense research is outlined. In view of that and recent progress of the theory of pseudodifferential boundary operator calculus, the author describes some features that could prove to be interesting in connection with the problems of boundary feedback...... stabilizability. It is shown that it is possible to use the calculus to consider more general feedback systems in a variational setup....

  9. Fuzzy Boundary and Fuzzy Semiboundary

    OpenAIRE

    M. Athar; B. Ahmad

    2008-01-01

    We present several properties of fuzzy boundary and fuzzy semiboundary which have been supported by examples. Properties of fuzzy semi-interior, fuzzy semiclosure, fuzzy boundary, and fuzzy semiboundary have been obtained in product-related spaces. We give necessary conditions for fuzzy continuous (resp., fuzzy semicontinuous, fuzzy irresolute) functions. Moreover, fuzzy continuous (resp., fuzzy semicontinuous, fuzzy irresolute) functions have been characterized via fuzzy-derived (resp., fuzz...

  10. On the elastic stiffness of grain boundaries

    International Nuclear Information System (INIS)

    Zhang Tongyi; Hack, J.E.

    1992-01-01

    The elastic softening of grain boundaries is evaluated from the starting point of grain boundary energy. Several examples are given to illustrate the relationship between boundary energy and the extent of softening. In general, a high grain boundary energy is associated with a large excess atomic volume in the boundary region. The consequent reduction in grain boundary stiffness can represent a significant fraction of that observed in bulk crystals. (orig.)

  11. Particle motion in atmospheric boundary layers of Mars and Earth

    Science.gov (United States)

    White, B. R.; Iversen, J. D.; Greeley, R.; Pollack, J. B.

    1975-01-01

    To study the eolian mechanics of saltating particles, both an experimental investigation of the flow field around a model crater in an atmospheric boundary layer wind tunnel and numerical solutions of the two- and three-dimensional equations of motion of a single particle under the influence of a turbulent boundary layer were conducted. Two-dimensional particle motion was calculated for flow near the surfaces of both Earth and Mars. For the case of Earth both a turbulent boundary layer with a viscous sublayer and one without were calculated. For the case of Mars it was only necessary to calculate turbulent boundary layer flow with a laminar sublayer because of the low values of friction Reynolds number; however, it was necessary to include the effects of slip flow on a particle caused by the rarefied Martian atmosphere. In the equations of motion the lift force functions were developed to act on a single particle only in the laminar sublayer or a corresponding small region of high shear near the surface for a fully turbulent boundary layer. The lift force functions were developed from the analytical work by Saffman concerning the lift force acting on a particle in simple shear flow.

  12. Seawater strontium isotopes at the Cretaceous-Tertiary boundary

    Science.gov (United States)

    Macdougall, J. D.; Martin, E.

    1988-01-01

    Anomalously high values of Seawater Sr-87/Sr-86 near the Cretaceous-Tertiary (K-T) boundary have been reported. However, few of the data from the literature are from a single continuous section, and perhaps the most complete study of the boundary region, from a shallow marine limestone sequence in Alabama, showed elevated Sr-87/Sr-86 but no pronounced spike. Thus, in order to investigate the cause of the change in strontium isotopic composition, it is important to determine the exact nature and magnitude of the increase by studying in detail continuous sections through the boundary. If there is indeed a Sr isotope spike at the K-T boundary, it requires the addition of a large amount of radiogenic Sr to the oceans over a short time period, a phenomenon that may be linked to other large-scale environmental disturbances which occurred at that time. In order to address this question, a high-resolution strontium isotope study of foraminifera from three Deep Sea Drilling Project (DSDP) cores which recovered the K-T boundary section: Site 356 in the South Atlantic, Site 384 in the North Atlantic and Site 577 from the Shatsky Rise in the Pacific was initiated. The isotope measurements are being made on either single or small numbers of forams carefully picked and identified and in most cases examined by SEM before analysis. Because this work is not yet complete, conclusions drawn here must be viewed as tentative. They are briefly discussed.

  13. Solution of moving boundary problems with implicit boundary condition

    International Nuclear Information System (INIS)

    Moyano, E.A.

    1990-01-01

    An algorithm that solves numerically a model for studying one dimensional moving boundary problems, with implicit boundary condition, is described. Landau's transformation is used, in order to work with a fixed number of nodes at each instant. Then, it is necessary to deal with a parabolic partial differential equation, whose diffusive and convective terms have variable coefficients. The partial differential equation is implicitly discretized, using Laasonen's scheme, always stable, instead of employing Crank-Nicholson sheme, as it has been done by Ferris and Hill. Fixed time and space steps (Δt, Δξ) are used, and the iteration is made with variable positions of the interface, i.e. varying δs until a boundary condition is satisfied. The model has the same features of the oxygen diffusion in absorbing tissue. It would be capable of estimating time variant radiation treatments of cancerous tumors. (Author) [es

  14. The boundary-scan handbook

    CERN Document Server

    Parker, Kenneth P

    2016-01-01

    Aimed at electronics industry professionals, this 4th edition of the Boundary Scan Handbook describes recent changes to the IEEE1149.1 Standard Test Access Port and Boundary-Scan Architecture. This updated edition features new chapters on the possible effects of the changes on the work of the practicing test engineers and the new 1149.8.1 standard. Anyone needing to understand the basics of boundary scan and its practical industrial implementation will need this book. Provides an overview of the recent changes to the 1149.1 standard and the effect of the changes on the work of test engineers;   Explains the new IEEE 1149.8.1 subsidiary standard and applications;   Describes the latest updates on the supplementary IEEE testing standards. In particular, addresses: IEEE Std 1149.1                      Digital Boundary-Scan IEEE Std 1149.4                      Analog Boundary-Scan IEEE Std 1149.6                      Advanced I/O Testing IEEE Std 1149.8.1           �...

  15. Distributed Tuning of Boundary Resources

    DEFF Research Database (Denmark)

    Eaton, Ben; Elaluf-Calderwood, Silvia; Sørensen, Carsten

    2015-01-01

    The digital age has seen the rise of service systems involving highly distributed, heterogeneous, and resource-integrating actors whose relationships are governed by shared institutional logics, standards, and digital technology. The cocreation of service within these service systems takes place...... in the context of a paradoxical tension between the logic of generative and democratic innovations and the logic of infrastructural control. Boundary resources play a critical role in managing the tension as a firm that owns the infrastructure can secure its control over the service system while independent...... firms can participate in the service system. In this study, we explore the evolution of boundary resources. Drawing on Pickering’s (1993) and Barrett et al.’s (2012) conceptualizations of tuning, the paper seeks to forward our understanding of how heterogeneous actors engage in the tuning of boundary...

  16. Asymptotic analysis and boundary layers

    CERN Document Server

    Cousteix, Jean

    2007-01-01

    This book presents a new method of asymptotic analysis of boundary-layer problems, the Successive Complementary Expansion Method (SCEM). The first part is devoted to a general comprehensive presentation of the tools of asymptotic analysis. It gives the keys to understand a boundary-layer problem and explains the methods to construct an approximation. The second part is devoted to SCEM and its applications in fluid mechanics, including external and internal flows. The advantages of SCEM are discussed in comparison with the standard Method of Matched Asymptotic Expansions. In particular, for the first time, the theory of Interactive Boundary Layer is fully justified. With its chapter summaries, detailed derivations of results, discussed examples and fully worked out problems and solutions, the book is self-contained. It is written on a mathematical level accessible to graduate and post-graduate students of engineering and physics with a good knowledge in fluid mechanics. Researchers and practitioners will estee...

  17. Physics of magnetospheric boundary layers

    Science.gov (United States)

    Cairns, Iver H.

    1995-01-01

    This final report was concerned with the ideas that: (1) magnetospheric boundary layers link disparate regions of the magnetosphere-solar wind system together; and (2) global behavior of the magnetosphere can be understood only by understanding its internal linking mechanisms and those with the solar wind. The research project involved simultaneous research on the global-, meso-, and micro-scale physics of the magnetosphere and its boundary layers, which included the bow shock, the magnetosheath, the plasma sheet boundary layer, and the ionosphere. Analytic, numerical, and simulation projects were performed on these subjects, as well as comparisons of theoretical results with observational data. Other related activity included in the research included: (1) prediction of geomagnetic activity; (2) global MHD (magnetohydrodynamic) simulations; (3) Alfven resonance heating; and (4) Critical Ionization Velocity (CIV) effect. In the appendixes are list of personnel involved, list of papers published; and reprints or photocopies of papers produced for this report.

  18. Boundary Spanners as supports of social capital

    DEFF Research Database (Denmark)

    Vincenti, Gordon

    2016-01-01

    Boundary Spanners are important agenets of supporting the capacity building of local neighbourhoods and of sustainable social captial the article focuses on the skills and competnces adn role of Boundary Spanners.......Boundary Spanners are important agenets of supporting the capacity building of local neighbourhoods and of sustainable social captial the article focuses on the skills and competnces adn role of Boundary Spanners....

  19. Boundary Value Problems and Approximate Solutions ...

    African Journals Online (AJOL)

    In this paper, we discuss about some basic things of boundary value problems. Secondly, we study boundary conditions involving derivatives and obtain finite difference approximations of partial derivatives of boundary value problems. The last section is devoted to determine an approximate solution for boundary value ...

  20. Boundary Transgressions: An Issue In Psychotherapeutic Encounter ...

    African Journals Online (AJOL)

    Boundary transgressions tend to be conceptualized on a continuum ranging from boundary crossings to boundary violations. Boundary crossings (e.g. accepting an inexpensive holiday gift from a client, unintentionally encountering a client in public, or attending a client's special event) are described in the literature as ...

  1. Second-Order Boundary Value Problem with Integral Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Nieto JuanJ

    2011-01-01

    Full Text Available The nonlinear alternative of the Leray Schauder type and the Banach contraction principle are used to investigate the existence of solutions for second-order differential equations with integral boundary conditions. The compactness of solutions set is also investigated.

  2. Boundary effect in electrorheological fluids.

    Science.gov (United States)

    Gong, X L; Yang, F; Xuan, S H; Zong, L H; Zhu, W; Jiang, W Q

    2011-12-01

    The effect of the boundary friction coefficient on the rheological properties of the electrorheological (ER) fluids in quasistatic and dynamic states is investigated by computer simulation. The relation between the shear stress and the boundary friction coefficient in quasistatic and dynamic states is discussed qualitatively and quantitatively, and the trend matches the previously reported experimental results well. The flow curves of ER fluids, under different friction coefficients, are calculated, and it is found that the friction coefficient affects the flow curves. In two dimensions, the transitions in structure corresponding to the shear stress variations are presented to understand the mechanism of ER fluids.

  3. Boundaries, work and the rest

    DEFF Research Database (Denmark)

    Bødker, Susanne

    summarize ways of doing that. From an understanding of the groups and communities involved, rather than from an understanding of the “places” of home and work, or from pre-perceived qualities of the two, can we understand the boundary drawing and how it is supported through collaborative technologies......This position paper takes its starting point in the definitions of work, and of boundaries often found in CSCW and HCI literature. By looking back at the case of parental leave planning and on my writings from the past 10 years, I discuss how these definitions need to be reconsidered, and I...

  4. Prediction of dislocation boundary characteristics

    DEFF Research Database (Denmark)

    Winther, Grethe

    orientation of the grain [1]. For selected boundaries it has been experimentally verified that the boundaries consist of fairly regular networks of dislocations, which come from the active slip systems [2]. The networks have been analyzed within the framework of Low-Energy-Dislocation-Structures (LEDS......, such as the dislocation content and misorientation. The prediction is based on the expected active slip systems and assumptions of mutual stress screening. In general, networks of dislocations with three linearly independent Burgers vectors fulfilling the criterion of mutual stress screening may form on any plane...

  5. Sausage mode stability boundaries: enumeration and verification

    International Nuclear Information System (INIS)

    Chambers, F.W.

    1980-01-01

    An axially symmetric sausage mode instability has been observed using particle simulation codes to propagate beams with a high degree of current neutralization. In this report the stability boundaries in terms of the magnitude and location of the return current are delineated for beams with square, Gaussian, and Bennett radial current profiles using the theoretical analysis of others. For the case in which the return current is held fixed as the beam propagates, a detailed comparison is made between the theoretical predictions and the results of the RINGFAST single disk particle simulation code. Agreement between theory and code results is good although the code results do show a slightly larger than predicted unstable region

  6. Dynamics of Coronal Hole Boundaries

    International Nuclear Information System (INIS)

    Higginson, A. K.; Zurbuchen, T. H.; Antiochos, S. K.; DeVore, C. R.; Wyper, P. F.

    2017-01-01

    Remote and in situ observations strongly imply that the slow solar wind consists of plasma from the hot, closed-field corona that is released onto open magnetic field lines. The Separatrix Web theory for the slow wind proposes that photospheric motions at the scale of supergranules are responsible for generating dynamics at coronal-hole boundaries, which result in the closed plasma release. We use three-dimensional magnetohydrodynamic simulations to determine the effect of photospheric flows on the open and closed magnetic flux of a model corona with a dipole magnetic field and an isothermal solar wind. A rotational surface motion is used to approximate photospheric supergranular driving and is applied at the boundary between the coronal hole and helmet streamer. The resulting dynamics consist primarily of prolific and efficient interchange reconnection between open and closed flux. The magnetic flux near the coronal-hole boundary experiences multiple interchange events, with some flux interchanging over 50 times in one day. Additionally, we find that the interchange reconnection occurs all along the coronal-hole boundary and even produces a lasting change in magnetic-field connectivity in regions that were not driven by the applied motions. Our results show that these dynamics should be ubiquitous in the Sun and heliosphere. We discuss the implications of our simulations for understanding the observed properties of the slow solar wind, with particular focus on the global-scale consequences of interchange reconnection.

  7. Humor styles and symbolic boundaries

    NARCIS (Netherlands)

    Kuipers, G.

    2009-01-01

    Humor is strongly related to group boundaries. Jokes and other humorous utterances often draw on implicit references and inside knowledge; they tend to refer to sensitive topics which may offend people; and they ideally incite laughter, one of the strongest markers of social solidarity and emotional

  8. Current Sinkhole Boundaries in Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This dataset is a polygon coverage of the sinkhole boundaries as determined by using LiDAR data. The polygons relate to the point coverage using the KPolyID field in...

  9. BRIDGES ACROSS AFRICA'S INTERNATIONAL BOUNDARIES ...

    African Journals Online (AJOL)

    The empirical data for this paper is drawn from the ethnic minorities divided along and astride the Cross River borderlands with southern Cameroon. Scholars who have studied the Nigeria Cameroon Boundary tend to lay more emphasis on the state centric perspective that continues to operate largely within the framework ...

  10. Editorial: Environmentalists without Boundaries | Ogunseitan ...

    African Journals Online (AJOL)

    African Journal of Environmental Science and Technology. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 3, No 3 (2009) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. Editorial: Environmentalists without Boundaries.

  11. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    ... tested using the coherence of time series to determine the causality and related orientation. The resulting link orientations at the plate boundary conditions indicate that causal triggering seems to be localized along a major fault, as a stress transfer between two major faults, and parallel to the geothermal area extension.

  12. Blurred Boundaries or Conflicting Epistemologies

    DEFF Research Database (Denmark)

    Mollerup, Nina Grønlykke

    2017-01-01

    of departure in anthropological fieldwork with information activists and journalists in Egypt, I show that information activists and journalists often had very similar practices and goals, which at times made the boundaries very blurry. Yet I argue that there was a significant distinction between...

  13. Coherent structures in wave boundary layers. Part 1. Oscillatory motion

    DEFF Research Database (Denmark)

    Carstensen, Stefan; Sumer, B. Mutlu; Fredsøe, Jørgen

    2010-01-01

    ) Vortex tubes, essentially two-dimensional vortices close to the bed extending across the width of the boundary-layer flow, caused by an inflectional-point shear layer instability. The imprint of these vortices in the bed shear stress is a series of small, insignificant kinks and dips. (ii) Turbulent......This work concerns oscillatory boundary layers over smooth beds. It comprises combined visual and quantitative techniques including bed shear stress measurements. The experiments were carried out in an oscillating water tunnel. The experiments reveal two significant coherent flow structures: (i...... spots, isolated arrowhead-shaped areas close to the bed in an otherwise laminar boundary layer where the flow ‘bursts’ with violent oscillations. The emergence of the turbulent spots marks the onset of turbulence. Turbulent spots cause single or multiple violent spikes in the bed shear stress signal...

  14. Numerical simulation of tsunami-scale wave boundary layers

    DEFF Research Database (Denmark)

    Williams, Isaac A.; Fuhrman, David R.

    2016-01-01

    This paper presents a numerical study of the boundary layer flow and properties induced by tsunami-scalewaves. For this purpose, an existing one-dimensional vertical (1DV) boundary layer model, based on the horizontal component of the incompressible Reynolds-averaged Navier–Stokes (RANS) equations...... demonstrating the ability to reproduce accurate velocity profiles, turbulence, and bed shear stresses on both smooth and rough beds.The validated model is then employed for the study of transient wave boundary layers at full tsunami scales,covering a wide and realistic geophysical range in terms of the flow...... duration, bottom roughness, and associated Reynolds numbers. For this purpose, three different “synthetic” (idealised) tsunami wave descriptions are considered i.e., invoking: (1) single wave (solitary-like, but with independent period and wave height),(2) sinusoidal, and (3) N-wave descriptions. The flow...

  15. Exploring the planetary boundary for chemical pollution.

    Science.gov (United States)

    Diamond, Miriam L; de Wit, Cynthia A; Molander, Sverker; Scheringer, Martin; Backhaus, Thomas; Lohmann, Rainer; Arvidsson, Rickard; Bergman, Åke; Hauschild, Michael; Holoubek, Ivan; Persson, Linn; Suzuki, Noriyuki; Vighi, Marco; Zetzsch, Cornelius

    2015-05-01

    Rockström et al. (2009a, 2009b) have warned that humanity must reduce anthropogenic impacts defined by nine planetary boundaries if "unacceptable global change" is to be avoided. Chemical pollution was identified as one of those boundaries for which continued impacts could erode the resilience of ecosystems and humanity. The central concept of the planetary boundary (or boundaries) for chemical pollution (PBCP or PBCPs) is that the Earth has a finite assimilative capacity for chemical pollution, which includes persistent, as well as readily degradable chemicals released at local to regional scales, which in aggregate threaten ecosystem and human viability. The PBCP allows humanity to explicitly address the increasingly global aspects of chemical pollution throughout a chemical's life cycle and the need for a global response of internationally coordinated control measures. We submit that sufficient evidence shows stresses on ecosystem and human health at local to global scales, suggesting that conditions are transgressing the safe operating space delimited by a PBCP. As such, current local to global pollution control measures are insufficient. However, while the PBCP is an important conceptual step forward, at this point single or multiple PBCPs are challenging to operationalize due to the extremely large number of commercial chemicals or mixtures of chemicals that cause myriad adverse effects to innumerable species and ecosystems, and the complex linkages between emissions, environmental concentrations, exposures and adverse effects. As well, the normative nature of a PBCP presents challenges of negotiating pollution limits amongst societal groups with differing viewpoints. Thus, a combination of approaches is recommended as follows: develop indicators of chemical pollution, for both control and response variables, that will aid in quantifying a PBCP(s) and gauging progress towards reducing chemical pollution; develop new technologies and technical and social

  16. Effects of boundary conditions on magnetization switching in kinetic ising models of nanoscale ferromagnets

    DEFF Research Database (Denmark)

    Richards, H.L.; Kolesik, M.; Lindgård, P.-A.

    1997-01-01

    Magnetization switching in highly anisotropic single-domain ferromagnets has been previously shown to be qualitatively described by the droplet theory of metastable decay and simulations of two-dimensional kinetic Ising systems with periodic boundary conditions. In this paper we consider the effe......Magnetization switching in highly anisotropic single-domain ferromagnets has been previously shown to be qualitatively described by the droplet theory of metastable decay and simulations of two-dimensional kinetic Ising systems with periodic boundary conditions. In this paper we consider...... simulations of two-dimensional Ising systems with various system shapes and boundary conditions....

  17. Grain Boundary Engineering of Electrodeposited Thin Films

    DEFF Research Database (Denmark)

    Alimadadi, Hossein

    Grain boundary engineering aims for a deliberate manipulation of the grain boundary characteristics to improve the properties of polycrystalline materials. Despite the emergence of some successful industrial applications, the mechanism(s) by which the boundary specific properties can be improved...... to engineer new materials. In this study, one of the most widely used electrolytes for electrodeposition is chosen for the synthesis of nickel films and based on thorough characterization of the boundaries the potentials in grain boundary engineering are outlined. The internal structure of the nickel films...... of the favorable boundaries that break the network of general grain boundaries. Successful dedicated synthesis of a textured nickel film fulfilling the requirements of grain boundary engineered materials, suggests improved boundary specific properties. However, the textured nickel film shows fairly low...

  18. Good Fences: The Importance of Setting Boundaries for Peaceful Coexistence

    Science.gov (United States)

    Rutherford, Alex; Harmon, Dion; Werfel, Justin; Gard-Murray, Alexander S.; Bar-Yam, Shlomiya; Gros, Andreas; Xulvi-Brunet, Ramon; Bar-Yam, Yaneer

    2014-01-01

    We consider the conditions of peace and violence among ethnic groups, testing a theory designed to predict the locations of violence and interventions that can promote peace. Characterizing the model's success in predicting peace requires examples where peace prevails despite diversity. Switzerland is recognized as a country of peace, stability and prosperity. This is surprising because of its linguistic and religious diversity that in other parts of the world lead to conflict and violence. Here we analyze how peaceful stability is maintained. Our analysis shows that peace does not depend on integrated coexistence, but rather on well defined topographical and political boundaries separating groups, allowing for partial autonomy within a single country. In Switzerland, mountains and lakes are an important part of the boundaries between sharply defined linguistic areas. Political canton and circle (sub-canton) boundaries often separate religious groups. Where such boundaries do not appear to be sufficient, we find that specific aspects of the population distribution guarantee either sufficient separation or sufficient mixing to inhibit intergroup violence according to the quantitative theory of conflict. In exactly one region, a porous mountain range does not adequately separate linguistic groups and that region has experienced significant violent conflict, leading to the recent creation of the canton of Jura. Our analysis supports the hypothesis that violence between groups can be inhibited by physical and political boundaries. A similar analysis of the area of the former Yugoslavia shows that during widespread ethnic violence existing political boundaries did not coincide with the boundaries of distinct groups, but peace prevailed in specific areas where they did coincide. The success of peace in Switzerland may serve as a model to resolve conflict in other ethnically diverse countries and regions of the world. PMID:24847861

  19. Good fences: the importance of setting boundaries for peaceful coexistence.

    Directory of Open Access Journals (Sweden)

    Alex Rutherford

    Full Text Available We consider the conditions of peace and violence among ethnic groups, testing a theory designed to predict the locations of violence and interventions that can promote peace. Characterizing the model's success in predicting peace requires examples where peace prevails despite diversity. Switzerland is recognized as a country of peace, stability and prosperity. This is surprising because of its linguistic and religious diversity that in other parts of the world lead to conflict and violence. Here we analyze how peaceful stability is maintained. Our analysis shows that peace does not depend on integrated coexistence, but rather on well defined topographical and political boundaries separating groups, allowing for partial autonomy within a single country. In Switzerland, mountains and lakes are an important part of the boundaries between sharply defined linguistic areas. Political canton and circle (sub-canton boundaries often separate religious groups. Where such boundaries do not appear to be sufficient, we find that specific aspects of the population distribution guarantee either sufficient separation or sufficient mixing to inhibit intergroup violence according to the quantitative theory of conflict. In exactly one region, a porous mountain range does not adequately separate linguistic groups and that region has experienced significant violent conflict, leading to the recent creation of the canton of Jura. Our analysis supports the hypothesis that violence between groups can be inhibited by physical and political boundaries. A similar analysis of the area of the former Yugoslavia shows that during widespread ethnic violence existing political boundaries did not coincide with the boundaries of distinct groups, but peace prevailed in specific areas where they did coincide. The success of peace in Switzerland may serve as a model to resolve conflict in other ethnically diverse countries and regions of the world.

  20. Good fences: the importance of setting boundaries for peaceful coexistence.

    Science.gov (United States)

    Rutherford, Alex; Harmon, Dion; Werfel, Justin; Gard-Murray, Alexander S; Bar-Yam, Shlomiya; Gros, Andreas; Xulvi-Brunet, Ramon; Bar-Yam, Yaneer

    2014-01-01

    We consider the conditions of peace and violence among ethnic groups, testing a theory designed to predict the locations of violence and interventions that can promote peace. Characterizing the model's success in predicting peace requires examples where peace prevails despite diversity. Switzerland is recognized as a country of peace, stability and prosperity. This is surprising because of its linguistic and religious diversity that in other parts of the world lead to conflict and violence. Here we analyze how peaceful stability is maintained. Our analysis shows that peace does not depend on integrated coexistence, but rather on well defined topographical and political boundaries separating groups, allowing for partial autonomy within a single country. In Switzerland, mountains and lakes are an important part of the boundaries between sharply defined linguistic areas. Political canton and circle (sub-canton) boundaries often separate religious groups. Where such boundaries do not appear to be sufficient, we find that specific aspects of the population distribution guarantee either sufficient separation or sufficient mixing to inhibit intergroup violence according to the quantitative theory of conflict. In exactly one region, a porous mountain range does not adequately separate linguistic groups and that region has experienced significant violent conflict, leading to the recent creation of the canton of Jura. Our analysis supports the hypothesis that violence between groups can be inhibited by physical and political boundaries. A similar analysis of the area of the former Yugoslavia shows that during widespread ethnic violence existing political boundaries did not coincide with the boundaries of distinct groups, but peace prevailed in specific areas where they did coincide. The success of peace in Switzerland may serve as a model to resolve conflict in other ethnically diverse countries and regions of the world.

  1. Single-molecule FRET reveals multiscale chromatin dynamics modulated by HP1α.

    Science.gov (United States)

    Kilic, Sinan; Felekyan, Suren; Doroshenko, Olga; Boichenko, Iuliia; Dimura, Mykola; Vardanyan, Hayk; Bryan, Louise C; Arya, Gaurav; Seidel, Claus A M; Fierz, Beat

    2018-01-16

    The dynamic architecture of chromatin fibers, a key determinant of genome regulation, is poorly understood. Here, we employ multimodal single-molecule Förster resonance energy transfer studies to reveal structural states and their interconversion kinetics in chromatin fibers. We show that nucleosomes engage in short-lived (micro- to milliseconds) stacking interactions with one of their neighbors. This results in discrete tetranucleosome units with distinct interaction registers that interconvert within hundreds of milliseconds. Additionally, we find that dynamic chromatin architecture is modulated by the multivalent architectural protein heterochromatin protein 1α (HP1α), which engages methylated histone tails and thereby transiently stabilizes stacked nucleosomes. This compacted state nevertheless remains dynamic, exhibiting fluctuations on the timescale of HP1α residence times. Overall, this study reveals that exposure of internal DNA sites and nucleosome surfaces in chromatin fibers is governed by an intrinsic dynamic hierarchy from micro- to milliseconds, allowing the gene regulation machinery to access compact chromatin.

  2. Exact and Optimal Quantum Mechanics/Molecular Mechanics Boundaries.

    Science.gov (United States)

    Sun, Qiming; Chan, Garnet Kin-Lic

    2014-09-09

    Motivated by recent work in density matrix embedding theory, we define exact link orbitals that capture all quantum mechanical (QM) effects across arbitrary quantum mechanics/molecular mechanics (QM/MM) boundaries. Exact link orbitals are rigorously defined from the full QM solution, and their number is equal to the number of orbitals in the primary QM region. Truncating the exact set yields a smaller set of link orbitals optimal with respect to reproducing the primary region density matrix. We use the optimal link orbitals to obtain insight into the limits of QM/MM boundary treatments. We further analyze the popular general hybrid orbital (GHO) QM/MM boundary across a test suite of molecules. We find that GHOs are often good proxies for the most important optimal link orbital, although there is little detailed correlation between the detailed GHO composition and optimal link orbital valence weights. The optimal theory shows that anions and cations cannot be described by a single link orbital. However, expanding to include the second most important optimal link orbital in the boundary recovers an accurate description. The second optimal link orbital takes the chemically intuitive form of a donor or acceptor orbital for charge redistribution, suggesting that optimal link orbitals can be used as interpretative tools for electron transfer. We further find that two optimal link orbitals are also sufficient for boundaries that cut across double bonds. Finally, we suggest how to construct "approximately" optimal link orbitals for practical QM/MM calculations.

  3. Pressure effect on grain boundary diffusion

    International Nuclear Information System (INIS)

    Smirnova, E.S.; Chuvil'deev, V.N.

    1997-01-01

    The influence of hydrostatic pressure on grain boundary diffusion and grain boundary migration in metallic materials is theoretically investigated. The model is suggested that permits describing changes in activation energy of grain boundary self-diffusion and diffusion permeability of grain boundaries under hydrostatic pressure. The model is based on the ideas about island-type structure of grain boundaries as well as linear relationship of variations in grain boundary free volume to hydrostatic pressure value. Comparison of theoretical data with experimental ones for a number of metals and alloys (α-Zr, Sn-Ge, Cu-In with Co, In, Al as diffusing elements) shows a qualitative agreement

  4. Decision boundary feature extraction for neural networks

    Science.gov (United States)

    Lee, Chulhee; Landgrebe, David A.

    1992-01-01

    We propose a new feature extraction method for neural networks. The method is based on the recently published decision boundary feature extraction algorithm. It has been shown that all the necessary features for classification can be extracted from the decision boundary. To apply the decision boundary feature extraction method, we first define the decision boundary in neural networks. Next, we propose a procedure for extracting all the necessary features for classification from the decision boundary. The proposed algorithm preserves the characteristics of neural networks, which can define arbitrary decision boundary. Experiments show promising results.

  5. Low temperature phonon boundary scattering in slightly rough Silicon nanowires

    Science.gov (United States)

    Ghossoub, Marc; Valavala, Krishna; Seong, Myunghoon; Azeredo, Bruno; Sadhu, Jyothi S.; Sinha, Sanjiv

    2013-03-01

    Nanostructured materials have lower thermal conductivities than the bulk and are promising candidates for thermoelectric applications. In particular, measurements on single silicon nanowires show a reduction in thermal conductivity below the Casimir limit. This reduction increases with surface roughness but the trend and its connection to phonon boundary scattering are still elusive. Here, we measure the thermal conductivity of single silicon nanowires fabricated using metal-assisted chemical etching. High resolution TEM imaging shows crystalline wires with slightly rough surfaces. Their statistical correlation lengths (5-15 nm) and RMS heights (0.8-1.5 nm) are in a range where perturbation-based wave scattering theory is still applicable. We use the thermal conductivity data to extract the frequency dependence of phonon boundary scattering at low temperatures (10-40 K) and show agreement with multiple scattering theory. This work provides insight into enhancing the thermoelectric performance of nanostructures.

  6. Plasma boundary phenomena in tokamaks

    International Nuclear Information System (INIS)

    Stangeby, P.C.

    1989-06-01

    The focus of this review is on processes occurring at the edge, and on the connection between boundary plasma - the scrape-off layer (SOL) and the radiating layer - and central plasma processes. Techniques used for edge diagnosis are reviewed and basic experimental information (n e and T e ) is summarized. Simple models of the SOL are summarized, and the most important effects of the boundary plasma - the influence on the fuel particles, impurities, and energy - on tokamak operation dealt with. Methods of manipulating and controlling edge conditions in tokamaks and the experimental data base for the edge during auxiliary heating of tokamaks are reviewed. Fluctuations and asymmetries at the edge are also covered. (9 tabs., 134 figs., 879 refs.)

  7. Helmholtz bright and boundary solitons

    International Nuclear Information System (INIS)

    Christian, J M; McDonald, G S; Chamorro-Posada, P

    2007-01-01

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts

  8. Information dynamics of boundary perception

    DEFF Research Database (Denmark)

    Kragness, Haley; Hansen, Niels Christian; Vuust, Peter

    -paced listening to chord sequences in a lab setting (the musical dwell-time effect). However, the origin of the musical dwell-time effect is still unknown. Recent work has demonstrated that musicians and non-musicians are sensitive to entropy in musical sequences, experiencing high-entropy contexts as more...... entropy (as estimated by the Information Dynamics of Music Model, IDyOM, trained on a large corpus of hymns and folksongs). Data collection is ongoing. The main analysis will examine whether longer dwelling is associated with boundary status or entropy. Results from this study will extend recent work...... on predictive uncertainty to the timing domain, as well as potentially answer key questions relating to boundary perception in musical listening....

  9. Social Entrepreneurship: Definition and Boundaries

    Directory of Open Access Journals (Sweden)

    Samer Abu-Saifan

    2012-02-01

    Full Text Available While individuals may be publicly recognized as social entrepreneurs for their contributions to improve the welfare of communities, the field of social entrepreneurship continues to struggle to gain academic legitimacy. Social entrepreneurship is a term in search of a good definition. The current use of the term seems vague and limitless; it needs boundaries to demarcate its function. The lack of a common definition hinders research and raises questions about which social or profit-making activities fall within the spectrum of social entrepreneurship. To become an important stream in the entrepreneurship literature, social entrepreneurship needs to be properly defined and it requires a theoretical framework that links it to the theory of entrepreneurship. This article builds on the literature to define social entrepreneurship, discusses the boundaries of socially-oriented entrepreneurial activities, and positions the social entrepreneur in the spectrum of entrepreneurship.

  10. Phase Transitions and Free Boundaries

    Science.gov (United States)

    1991-10-31

    V PHASE TRANSITIONS AND FREE BOUNDARIES FINAL REPORT AD -A243 412 DECO 3 1991 WILLARD MILLER, JR. U October 31, 1991 OFFICE OF NAVAL RESEARCH N0014-91...Einstein- University of Michigan Yang/Mills equations Abstract: The only static solution to the vacuum Einstein equations is the celebrated Schwarzschild ...equations to Maxwell’s equations, the only static solution is the Reissner- Nordstr6m metric which is again singular at the origin. Finally, for any gauge

  11. Sensitivity to volcanic field boundary

    Science.gov (United States)

    Runge, Melody; Bebbington, Mark; Cronin, Shane; Lindsay, Jan; Rashad Moufti, Mohammed

    2016-04-01

    Volcanic hazard analyses are desirable where there is potential for future volcanic activity to affect a proximal population. This is frequently the case for volcanic fields (regions of distributed volcanism) where low eruption rates, fertile soil, and attractive landscapes draw populations to live close by. Forecasting future activity in volcanic fields almost invariably uses spatial or spatio-temporal point processes with model selection and development based on exploratory analyses of previous eruption data. For identifiability reasons, spatio-temporal processes, and practically also spatial processes, the definition of a spatial region is required to which volcanism is confined. However, due to the complex and predominantly unknown sub-surface processes driving volcanic eruptions, definition of a region based solely on geological information is currently impossible. Thus, the current approach is to fit a shape to the known previous eruption sites. The class of boundary shape is an unavoidable subjective decision taken by the forecaster that is often overlooked during subsequent analysis of results. This study shows the substantial effect that this choice may have on even the simplest exploratory methods for hazard forecasting, illustrated using four commonly used exploratory statistical methods and two very different regions: the Auckland Volcanic Field, New Zealand, and Harrat Rahat, Kingdom of Saudi Arabia. For Harrat Rahat, sensitivity of results to boundary definition is substantial. For the Auckland Volcanic Field, the range of options resulted in similar shapes, nevertheless, some of the statistical tests still showed substantial variation in results. This work highlights the fact that when carrying out any hazard analysis on volcanic fields, it is vital to specify how the volcanic field boundary has been defined, assess the sensitivity of boundary choice, and to carry these assumptions and related uncertainties through to estimates of future activity and

  12. Applied thermodynamics: Grain boundary segregation

    Czech Academy of Sciences Publication Activity Database

    Lejček, Pavel; Zheng, L.; Hofmann, S.; Šob, Mojmír

    2014-01-01

    Roč. 16, č. 3 (2014), s. 1462-1484 ISSN 1099-4300 R&D Projects: GA ČR(CZ) GAP108/12/0311; GA ČR GAP108/12/0144; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68378271 ; RVO:68081723 Keywords : interfacial segregation * Gibbs energy of segregation * enthalpy * entropy * volume * grain boundaries * iron Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.502, year: 2014

  13. Working across Boundaries in Design

    DEFF Research Database (Denmark)

    Clausen, Christian; Yoshinaka, Yutaka

    The paper addresses how insights from the social shaping tradition and political process theory may contribute to an understanding of design as staging of sociotechnical relations and processes cutting across boundaries of diverse organisational, political and knowledge domains. This idea is purs...... organisational practices. One implication of this approach includes an attention towards what (and how) ar-eas may be rendered open to negotiation and transformation in technological design, implementation, and change processes....

  14. Borders, boundaries and desirable wishes

    Directory of Open Access Journals (Sweden)

    Luca Pinciaroli

    2015-05-01

    Full Text Available “Borders, boundaries and desirable wishes” is the title of the residential workshop offered to a group of young adults (aged 18-25 of the Centro di Salute Mentale (Mental Health Center of the DSM Basaglia of ASL TO2 in Turin. The idea of the workshop, the definition of the objectives and the topics, which are clearly expressed in the title, come from the work of the team dedicated to group psychotherapies, which has been offering group psychodrama sessions to young adults of this age since 2008. In the delicate move to the adult age, these young adults are lost and stuck in static realities where it is not possible to open up to the dimension of desire nor to the transforming encounter with the Other, since they didn’t have the experience of boundaries and lack. These two elements are necessary to acquire the ability to make projects for oneself. During the workshop the following instruments were used: group, psychodrama and art therapy. The group, as a paternal function, ensured the presence of safe boundaries enabling individuals to experiment; psychodrama and art therapy enabled the bodies to experience encounters and transformations, using doing as a metaphor for the movement against the inhibition of doing and as a way to show oneself to the Other and be able to see the Other. 

  15. Integrability and boundary conditions of supersymmetric systems

    International Nuclear Information System (INIS)

    Yue Ruihong; Liang Hong

    1996-01-01

    By studying the solutions of the reflection equations, we find out a series of integrable supersymmetric systems with different boundary conditions. The Hamiltonian contains four free parameters which describe the contribution of the boundary terms

  16. Cal State Park Boundaries 2011/2012

    Data.gov (United States)

    California Natural Resource Agency — This is a GIS version of California State Park (CSP) operational boundaries and does not represent official property boundary determinations. This GIS version is...

  17. Grain boundaries in Ni3Al. 2

    International Nuclear Information System (INIS)

    Kung, H.; Sass, S.L.

    1992-01-01

    This paper discusses the dislocation structure of small angle tilt and twist boundaries in ordered Ni 3 Al, with and without boron, investigated using transmission electron microscopy. Dislocation with Burgers vectors that correspond to anti-phase boundary (APB)-coupled superpartials were found in small angle twist boundaries in both boron-free and boron-doped Ni 3 Al, and a small angle tilt boundary in boron-doped Ni 3 Al. The boundary structures are in agreement with theoretical models proposed by Marcinkowski and co-workers. The APB energy determined from the dissociation of the grain boundary dislocations was lower than values reported for isolated APBs in Ni 3 Al. For small angle twist boundaries the presence of boron reduced the APB energy at the interface until it approached zero. This is consistent with the structure of these boundaries containing small regions of increased compositional disorder in the first atomic plane next to the interface

  18. Practical boundary surveying legal and technical principles

    CERN Document Server

    Gay, Paul

    2015-01-01

    This guide to boundary surveying provides landowners, land surveyors, students and others with the necessary foundation to understand boundary surveying techniques and the common legal issues that govern boundary establishment.  Boundary surveying is sometimes mistakenly considered a strictly technical discipline with simple and straightforward technical solutions.  In reality, boundary establishment is often a difficult and complex matter, requiring years of experience and a thorough understanding of boundary law.  This book helps readers to understand the challenges often encountered by boundary surveyors and some of the available solutions. Using only simple and logically explained mathematics, the principles and practice of boundary surveying are demystified for those without prior experience, and the focused coverage of pivotal issues such as easements and setting lot corners will aid even licensed practitioners in untangling thorny cases. Practical advice on using both basic and advanced instruments ...

  19. Cal State Park Boundaries 2011/2012

    Data.gov (United States)

    California Department of Resources — This is a GIS version of California State Park (CSP) operational boundaries and does not represent official property boundary determinations. This GIS version is...

  20. Flat Plate Boundary Layer Stimulation Using Trip Wires and Hama Strips

    Science.gov (United States)

    Peguero, Charles; Henoch, Charles; Hrubes, James; Fredette, Albert; Roberts, Raymond; Huyer, Stephen

    2017-11-01

    Water tunnel experiments on a flat plate at zero angle of attack were performed to investigate the effect of single roughness elements, i.e., trip wires and Hama strips, on the transition to turbulence. Boundary layer trips are traditionally used in scale model testing to force a boundary layer to transition from laminar to turbulent flow at a single location to aid in scaling of flow characteristics. Several investigations of trip wire effects exist in the literature, but there is a dearth of information regarding the influence of Hama strips on the flat plate boundary layer. The intent of this investigation is to better understand the effects of boundary layer trips, particularly Hama strips, and to investigate the pressure-induced drag of both styles of boundary layer trips. Untripped and tripped boundary layers along a flat plate at a range of flow speeds were characterized with multiple diagnostic measurements in the NUWC/Newport 12-inch water tunnel. A wide range of Hama strip and wire trip thicknesses were used. Measurements included dye flow visualization, direct skin friction and parasitic drag force, boundary layer profiles using LDV, wall shear stress fluctuations using hot film anemometry, and streamwise pressure gradients. Test results will be compared to the CFD and boundary layer model results as well as the existing body of work. Conclusions, resulting in guidance for application of Hama strips in model scale experiments and non-dimensional predictions of pressure drag will be presented.

  1. Quantum cavities with alternating boundary conditions

    Science.gov (United States)

    Facchi, Paolo; Garnero, Giancarlo; Ligabò, Marilena

    2018-03-01

    We consider the quantum dynamics of a free nonrelativistic particle moving in a cavity and we analyze the effect of a rapid switching between two different boundary conditions. We show that this procedure induces, in the limit of infinitely frequent switchings, a new effective dynamics in the cavity related to a novel boundary condition. We obtain a dynamical composition law for boundary conditions which gives the emerging boundary condition in terms of the two initial ones.

  2. Boundary controllability of integrodifferential systems in Banach ...

    Indian Academy of Sciences (India)

    [6] discussed the general theory of boundary control systems. Barbu and Precupanu [4] studied a class of convex control problems governed by linear evolution systems covering the principal boundary control systems of parabolic type. In [5] Barbu investigated a class of boundary-distributed linear control systems in ...

  3. Transient Solute Drag in Migrating Grain Boundaries

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří; Fischer, F. D.; Liendl, M.

    2011-01-01

    Roč. 59, č. 17 (2011), s. 6556-6562 ISSN 1359-6454 R&D Projects: GA MŠk(CZ) OC10029 Institutional research plan: CEZ:AV0Z20410507 Keywords : Grain boundary diffusion * Grain boundary migration * Grain boundary segregation Subject RIV: BJ - Thermodynamic s Impact factor: 3.755, year: 2011

  4. Acoustic reflection from the boundary of anisotropic ...

    Indian Academy of Sciences (India)

    Vertical slownesses of waves at a boundary of an anisotropic thermoviscoelastic medium are calculated as roots of a polynomial equation of degree eight. Out of the corresponding eight waves, the four, which travel towards the boundary are identified as upgoing waves. Remaining four waves travel away from the boundary ...

  5. Slip patterns and preferred dislocation boundary planes

    DEFF Research Database (Denmark)

    Winther, G.

    2003-01-01

    and polycrystals of fcc metals in three deformation modes (rolling, tension and torsion). In the macroscopic system, boundaries lie close to the macroscopically most stressed planes. In the crystallographic system, the boundary plane depends on the grain/crystal orientation. The boundary planes in both co...

  6. Determination of grain boundary geometry using TEM

    NARCIS (Netherlands)

    Jang, H.; Farkas, D.; Hosson, J.T.M. De

    An experimental method to obtain the grain boundary geometry using the transmission electron microscope is presented. The method allows Σ determination including grain boundary plane orientation. In order to determine the specialness of the grain boundary, three different criteria for maximum

  7. Free-Boundary Resistive Modes in Tokamaks

    NARCIS (Netherlands)

    Huysmans, G. T. A.; Goedbloed, J. P.; Kerner, W.

    1993-01-01

    There exist a number of observations of magnetohydrodynamic (MHD) activity that can be related to resistive MHD modes localized near the plasma boundary. To study the stability of these modes, a free boundary description of the plasma is essential. The resistive plasma-vacuum boundary conditions

  8. Performing boundary work: The emergence of a new practice in a hybrid operating room.

    Science.gov (United States)

    Lindberg, Kajsa; Walter, Lars; Raviola, Elena

    2017-06-01

    This paper addresses the processes of boundary work, in relation to the introduction of new technology, unfolding during the emergence of new medical practices. Inspired by Gieryn's fluid and practical view of boundaries and boundary work, and by Actor-Network Theory's description of scripting processes, we study the processes of negotiating and (re-)constructing boundaries in order to reveal both the interactions between different kinds of boundary work and their situatedness in the context of the emerging practice. We conducted a longitudinal and qualitative study of a generic Hybrid Operating Room at a Swedish university hospital, where sophisticated imaging devices are combined with open surgery procedures in a single room; consequently, medical requirements regarding radiology, surgery and anesthesia, as well as the specificities of the new technology, all need to be met at the same time. The study shows how the visibility of boundaries is a result of as well as a condition for boundary work, how boundary work is a dynamic and iterative process, and how it unfolds in a recursive relationship between practice and boundaries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Second order bounce back boundary condition for the lattice Boltzmann fluid simulation

    International Nuclear Information System (INIS)

    Kim, In Chan

    2000-01-01

    A new bounce back boundary method of the second order in error is proposed for the lattice Boltzmann fluid simulation. This new method can be used for the arbitrarily irregular lattice geometry of a non-slip boundary. The traditional bounce back boundary condition for the lattice Boltzmann simulation is of the first order in error. Since the lattice Boltzmann method is the second order scheme by itself, a boundary technique of the second order has been desired to replace the first order bounce back method. This study shows that, contrary to the common belief that the bounce back boundary condition is unilaterally of the first order, the second order bounce back boundary condition can be realized. This study also shows that there exists a generalized bounce back technique that can be characterized by a single interpolation parameter. The second order bounce back method can be obtained by proper selection of this parameter in accordance with the detailed lattice geometry of the boundary. For an illustrative purpose, the transient Couette and the plane Poiseuille flows are solved by the lattice Boltzmann simulation with various boundary conditions. The results show that the generalized bounce back method yields the second order behavior in the error of the solution, provided that the interpolation parameter is properly selected. Coupled with its intuitive nature and the ease of implementation, the bounce back method can be as good as any second order boundary method

  10. Persistent Identifiers as Boundary Objects

    Science.gov (United States)

    Parsons, M. A.; Fox, P. A.

    2017-12-01

    In 1989, Leigh Star and Jim Griesemer defined the seminal concept of `boundary objects'. These `objects' are what Latour calls `immutable mobiles' that enable communication and collaboration across difference by helping meaning to be understood in different contexts. As Star notes, they are a sort of arrangement that allow different groups to work together without (a priori) consensus. Part of the idea is to recognize and allow for the `interpretive flexibility' that is central to much of the `constructivist' approach in the sociology of science. Persistent Identifiers (PIDs) can clearly act as boundary objects, but people do not usually assume that they enable interpretive flexibility. After all, they are meant to be unambiguous, machine-interpretable identifiers of defined artifacts. In this paper, we argue that PIDs can fill at least two roles: 1) That of the standardized form, where there is strong agreement on what is being represented and how and 2) that of the idealized type, a more conceptual concept that allows many different representations. We further argue that these seemingly abstract conceptions actually help us implement PIDs more effectively to link data, publications, various other artifacts, and especially people. Considering PIDs as boundary objects can help us address issues such as what level of granularity is necessary for PIDs, what metadata should be directly associated with PIDs, and what purpose is the PID serving (reference, provenance, credit, etc.). In short, sociological theory can improve data sharing standards and their implementation in a way that enables broad interdisciplinary data sharing and reuse. We will illustrate this with several specific examples of Earth science data.

  11. Applied Thermodynamics: Grain Boundary Segregation

    Directory of Open Access Journals (Sweden)

    Pavel Lejček

    2014-03-01

    Full Text Available Chemical composition of interfaces—free surfaces and grain boundaries—is generally described by the Langmuir–McLean segregation isotherm controlled by Gibbs energy of segregation. Various components of the Gibbs energy of segregation, the standard and the excess ones as well as other thermodynamic state functions—enthalpy, entropy and volume—of interfacial segregation are derived and their physical meaning is elucidated. The importance of the thermodynamic state functions of grain boundary segregation, their dependence on volume solid solubility, mutual solute–solute interaction and pressure effect in ferrous alloys is demonstrated.

  12. On SLE Martingales in Boundary WZW Models

    Science.gov (United States)

    Alekseev, Anton; Bytsko, Andrei; Izyurov, Konstantin

    2011-09-01

    Following Bettelheim et al. (Phys Rev Lett 95:251601, 2005), we consider the boundary WZW model on a half-plane with a cut growing according to the Schramm-Loewner stochastic evolution and the boundary fields inserted at the tip of the cut and at infinity. We study necessary and sufficient conditions for boundary correlation functions to be SLE martingales. Necessary conditions come from the requirement for the boundary field at the tip of the cut to have a depth two null vector. Sufficient conditions are established using Knizhnik-Zamolodchikov equations for boundary correlators. Combining these two approaches, we show that in the case of G = SU(2) the boundary correlator is an SLE martingale if and only if the boundary field carries spin 1/2. In the case of G = SU( n) and the level k = 1, there are several situations when boundary one-point correlators are SLE κ -martingales. If the boundary field is labelled by the defining n-dimensional representation of SU( n), we obtain {\\varkappa=2} . For n even, by choosing the boundary field labelled by the (unique) self-adjoint fundamental representation, we get {\\varkappa=8/(n {+} 2)} . We also study the situation when the distance between the two boundary fields is finite, and we show that in this case the {SLE_\\varkappa} evolution is replaced by {SLE_{\\varkappa,ρ}} with {ρ=\\varkappa -6}.

  13. Stress propagation in isotropic packs with anisotropic boundaries

    Science.gov (United States)

    Krapf, Nathan; Witten, Thomas

    2010-03-01

    Stresses in marginally jammed, anisotropic packs built up from a solid floor propagate along oblique rays toward the floor footnotetext D. A. Head, A. V. Tkachenko, and T. A. Witten. Eur. Phys. J. E 6, 99-105 (2001)). This clear anisotropic propagation must result from anisotropic packing and/or anisotropic boundary conditions. Here we numerically isolate the effect of anisotropic boundaries by using an explicitly isotropic periodic pack in a marginally jammed, isostatic state. We then remove the periodicity in one direction and anchor the beads along one edge to a substrate. This preserves the isostatic condition while rendering the boundary anisotropic. However, we find hyperstatic modes along one edge of the pack and hypostatic modes at the other. We show that these extra modes decay rapidly away from the boundaries. Remarkably the hypostatic modes cause the pack to be unstable under any force applied to a single bead. This instability can be remedied by applying a suitable cluster of forces to adjacent beads, allowing a clear measurement of the bulk response. We discuss the resulting stress response.

  14. Boundary conditions for open quantum systems driven far from equilibrium

    Science.gov (United States)

    Frensley, William R.

    1990-07-01

    This is a study of simple kinetic models of open systems, in the sense of systems that can exchange conserved particles with their environment. The system is assumed to be one dimensional and situated between two particle reservoirs. Such a system is readily driven far from equilibrium if the chemical potentials of the reservoirs differ appreciably. The openness of the system modifies the spatial boundary conditions on the single-particle Liouville-von Neumann equation, leading to a non-Hermitian Liouville operator. If the open-system boundary conditions are time reversible, exponentially growing (unphysical) solutions are introduced into the time dependence of the density matrix. This problem is avoided by applying time-irreversible boundary conditions to the Wigner distribution function. These boundary conditions model the external environment as ideal particle reservoirs with properties analogous to those of a blackbody. This time-irreversible model may be numerically evaluated in a discrete approximation and has been applied to the study of a resonant-tunneling semiconductor diode. The physical and mathematical properties of the irreversible kinetic model, in both its discrete and its continuum formulations, are examined in detail. The model demonstrates the distinction in kinetic theory between commutator superoperators, which may become non-Hermitian to describe irreversible behavior, and anticommutator superoperators, which remain Hermitian and are used to evaluate physical observables.

  15. Boundary element simulation of petroleum reservoirs with hydraulically fractured wells

    Science.gov (United States)

    Pecher, Radek

    The boundary element method is applied to solve the linear pressure-diffusion equation of fluid-flow in porous media. The governing parabolic partial differential equation is transformed into the Laplace space to obtain the elliptic modified-Helmholtz equation including the homogeneous initial condition. The free- space Green's functions, satisfying this equation for anisotropic media in two and three dimensions, are combined with the generalized form of the Green's second identity. The resulting boundary integral equation is solved by following the collocation technique and applying the given time-dependent boundary conditions of the Dirichlet or Neumann type. The boundary integrals are approximated by the Gaussian quadrature along each element of the discretized domain boundary. Heterogeneous regions are represented by the sectionally-homogeneous zones of different rock and fluid properties. The final values of the interior pressure and velocity fields and of their time-derivatives are found by numerically inverting the solutions from the Laplace space by using the Stehfest's algorithm. The main extension of the mostly standard BEM-procedure is achieved in the modelling of the production and injection wells represented by internal sources and sinks. They are treated as part of the boundary by means of special single-node and both-sided elements, corresponding to the line and plane sources respectively. The wellbore skin and storage effects are considered for the line and cylindrical sources. Hydraulically fractured wells of infinite conductivity are handled directly according to the specified constraint type, out of the four alternatives. Fractures of finite conductivity are simulated by coupling the finite element model of their 1D-interior with the boundary element model of their 2D- exterior. Variable fracture width, fractures crossing zone boundaries, ``networking'' of fractures, fracture-tip singularity handling, or the 3D-description are additional advanced

  16. The surface roughness and planetary boundary layer

    Science.gov (United States)

    Telford, James W.

    1980-03-01

    Applications of the entrainment process to layers at the boundary, which meet the self similarity requirements of the logarithmic profile, have been studied. By accepting that turbulence has dominating scales related in scale length to the height above the surface, a layer structure is postulated wherein exchange is rapid enough to keep the layers internally uniform. The diffusion rate is then controlled by entrainment between layers. It has been shown that theoretical relationships derived on the basis of using a single layer of this type give quantitatively correct factors relating the turbulence, wind and shear stress for very rough surface conditions. For less rough surfaces, the surface boundary layer can be divided into several layers interacting by entrainment across each interface. This analysis leads to the following quantitatively correct formula compared to published measurements. 1 24_2004_Article_BF00877766_TeX2GIFE1.gif {σ _w }/{u^* } = ( {2/{9Aa}} )^{{1/4}} ( {1 - 3^{{1/2}{ a/k{d_n }/z{σ _w }/{u^* }z/L} )^{{1/4}} = 1.28(1 - 0.945({{σ _w }/{u^* }}}) {{z/L}})^{{1/4 where u^* = ( {{tau/ρ}}^{{1/2}}, σ w is the standard deviation of the vertical velocity, z is the height and L is the Obukhov scale lenght. The constants a, A, k and d n are the entrainment constant, the turbulence decay constant, Von Karman's constant, and the layer depth derived from the theory. Of these, a and A, are universal constants and not empirically determined for the boundary layer. Thus the turbulence needed for the plume model of convection, which resides above these layers and reaches to the inversion, is determined by the shear stress and the heat flux in the surface layers. This model applies to convection in cool air over a warm sea. The whole field is now determined except for the temperature of the air relative to the water, and the wind, which need a further parameter describing sea surface roughness. As a first stop to describing a surface where roughness elements

  17. Using UAV's to Measure the Urban Boundary Layer

    Science.gov (United States)

    Jacob, R. L.; Sankaran, R.; Beckman, P. H.

    2015-12-01

    The urban boundary layer is one of the most poorly studied regions of the atmospheric boundary layer. Since a majority of the world's population now lives in urban areas, it is becoming a more important region to measure and model. The combination of relatively low-cost unmanned aerial vehicles and low-cost sensors can together provide a new instrument for measuring urban and other boundary layers. We have mounted a new sensor and compute platform called Waggle on an off-the-shelf XR8 octo-copter from 3DRobotics. Waggle consists of multiple sensors for measuring pressure, temperature and humidity as well as trace gases such as carbon monoxide, nitrogen dioxide, sulfur dioxide and ozone. A single board computer running Linux included in Waggle on the UAV allows in-situ processing and data storage. Communication of the data is through WiFi or 3G and the Waggle software can save the data in case communication is lost during flight. The flight pattern is a deliberately simple vertical ascent and descent over a fixed location to provide vertical profiles and so flights can be confined to urban parks, industrial areas or the footprint of a single rooftop. We will present results from test flights in urban and rural areas in and around Chicago.

  18. Microscale Liquid Transport in Polycrystalline Inverse Opals across Grain Boundaries.

    Science.gov (United States)

    Pham, Q N; Barako, M T; Tice, J; Won, Y

    2017-09-05

    Delivering liquid through the void spaces in porous metals is a daunting challenge for a variety of emerging interface technologies ranging from battery electrodes to evaporation surfaces. Hydraulic transport characteristics of well-ordered porous media are governed by the pore distribution, porosity, and morphology. Much like energy transport in polycrystalline solids, hydraulic transport in semi-ordered porous media is predominantly limited by defects and grain boundaries. Here, we report the wicking performances for porous copper inverse opals having pore diameters from 300 to 1000 nm by measuring the capillary-driven liquid rise. The capillary performance parameter within single crystal domain (K ij /R eff  = 10 -3 to 10 -2  µm) is an order of magnitude greater than the collective polycrystal (K eff /R eff  = ~10 -5 to 10 -3  µm) due to the hydraulic resistances (i.e. grain boundaries between individual grains). Inspired by the heterogeneity found in biological systems, we report that the capillary performance parameter of gradient porous copper (K eff /R eff  = ~10 -3  µm), comparable to that of single crystals, overcomes hydraulic resistances through providing additional hydraulic routes in three dimensions. The understanding of microscopic liquid transport physics through porous crystals and across grain boundaries will help to pave the way for the spatial design of next-generation heterogeneous porous media.

  19. On the existence of hydrodynamic instability in single diffusive ...

    Indian Academy of Sciences (India)

    existence of hydrodynamic instability in single diffusive bottom heavy systems, when considered in the more ... sive bottom heavy system, with permeable boundaries at which the boundary condition of Beavers and .... and this expression gives the critical Rayleigh number Rc = 27π4/4 (1 − α2T0) identical with that obtained ...

  20. Mixed basin boundary structures of chaotic systems

    International Nuclear Information System (INIS)

    Rosa, E. Jr.; Ott, E.

    1999-01-01

    Motivated by recent numerical observations on a four-dimensional continuous-time dynamical system, we consider different types of basin boundary structures for chaotic systems. These general structures are essentially mixtures of the previously known types of basin boundaries where the character of the boundary assumes features of the previously known boundary types at different points arbitrarily finely interspersed in the boundary. For example, we discuss situations where an everywhere continuous boundary that is otherwise smooth and differentiable at almost every point has an embedded uncountable, zero Lebesgue measure set of points at which the boundary curve is nondifferentiable. Although the nondifferentiable set is only of zero Lebesgue measure, the curve close-quote s fractal dimension may (depending on parameters) still be greater than one. In addition, we discuss bifurcations from such a mixed boundary to a 'pure' boundary that is a fractal nowhere differentiable curve or surface and to a pure nonfractal boundary that is everywhere smooth. copyright 1999 The American Physical Society

  1. Working with boundaries in systems psychodynamic consulting

    Directory of Open Access Journals (Sweden)

    Henk Struwig

    2012-03-01

    Research purpose: The purpose of the research was to produce a set of theoretical assumptions about organisational boundaries and boundary management in organisations and, from these, to develop a set of hypotheses as a thinking framework for practising consulting psychologists when they work with boundaries from a systems psychodynamic stance. Motivation for the study: The researcher used the belief that organisational boundaries reflect the essence of organisations. Consulting to boundary managers could facilitate a deep understanding of organisational dynamics. Research design, approach and method: The researcher followed a case study design. He used systems psychodynamic discourse analysis. It led to six working hypotheses. Main findings: The primary task of boundary management is to hold the polarities of integration and differentiation and not allow the system to become fragmented or overly integrated. Boundary management is a primary task and an ongoing activity of entire organisations. Practical/managerial implications: Organisations should work actively at effective boundary management and at balancing integration and differentiation. Leaders should become aware of how effective boundary management leads to good holding environments that, in turn, lead to containing difficult emotions in organisations. Contribution/value-add: The researcher provided a boundary-consulting framework in order to assist consultants to balance the conceptual with the practical when they consult.

  2. Influence of grain boundaries on elasticity and thermal conductivity of nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Mohr, Markus; Daccache, Layal; Horvat, Sebastian; Brühne, Kai; Jacob, Timo; Fecht, Hans-Jörg

    2017-01-01

    Diamond combines several outstanding material properties such as the highest thermal conductivity and highest elastic moduli of all materials. This makes diamond an interesting candidate for a multitude of applications. Nonetheless, nanocrystalline diamond films, layers and coatings, usually show properties different to those of single crystalline diamond. This is usually attributed to the larger volume fraction of the grain boundaries with atomic structure different from the single crystal. In this work we measured Young's modulus and thermal conductivity of nanocrystalline diamond films with average grain sizes ranging from 6 to 15 nm. The measured thermal conductivities are modeled considering the thermal boundary conductance between grains as well as a grain size effect on the phonon mean free path. We make a comparison between elastic modulus and thermal boundary conductance of the grain boundaries G k for different nanocrystalline diamond films. We conclude that the grain boundaries thermal boundary conductance G k is a measure of the cohesive energy of the grain boundaries and therefore also of the elastic modulus of the nanocrystalline diamond films.

  3. The evolution of disorientations for several types of boundaries

    DEFF Research Database (Denmark)

    Pantleon, W.

    2001-01-01

    During plastic deformation dislocation boundaries appear separating regions of different orientation. A model for the occurrence of disorientations across these boundaries is proposed and discussed with emphasis on several types of boundaries. For incidental dislocation boundaries a statistical...

  4. Analysis of grain boundaries, twin boundaries, and Te precipitates in CdZnTe grown by high-pressure Bridgeman method

    International Nuclear Information System (INIS)

    Heffelfinger, J.R.; Medlin, D.L.; James, R.B.

    1998-03-01

    Grain boundaries and twin boundaries in commercial Cd 1-x Zn x Te, which is prepared by a high pressure Bridgeman technique, have been investigated with transmission electron microscopy, scanning electron microscopy, infrared light microscopy and visible light microscopy. Boundaries inside these materials were found to be decorated with Te precipitates. The shape and local density of the precipitates were found to depend on the particular boundary. For precipitates that decorate grain boundaries, their microstructure was found to consist of a single, saucer shaped grain of hexagonal Te (space group P3 1 21). Analysis of a Te precipitate precipitates by selected area diffraction revealed the Te to be aligned with the surrounding Cd 1-x Zn x Te grains. This alignment was found to match the (111) Cd 1-x Z x Te planes with the (1 bar 101) planes of hexagonal Te. Crystallographic alignments between the Cd 1-x Zn x Te grains were also observed for a high angle grain boundary. The structure of the grain boundaries and the Te/Cd 1-x Zn x Te interface are discussed

  5. Outer Magnetospheric Boundaries Cluster Results

    CERN Document Server

    Paschmann, Goetz; Schwartz, S J

    2006-01-01

    When the stream of plasma emitted from the Sun (the solar wind) encounters Earth's magnetic field, it slows down and flows around it, leaving behind a cavity, the magnetosphere. The magnetopause is the surface that separates the solar wind on the outside from the Earth's magnetic field on the inside. Because the solar wind moves at supersonic speed, a bow shock must form ahead of the magnetopause that acts to slow the solar wind to subsonic speeds. Magnetopause, bow shock and their environs are rich in exciting processes in collisionless plasmas, such as shock formation, magnetic reconnection, particle acceleration and wave-particle interactions. They are interesting in their own right, as part of Earth's environment, but also because they are prototypes of similar structures and phenomena that are ubiquitous in the universe, having the unique advantage that they are accessible to in situ measurements. The boundaries of the magnetosphere have been the target of direct in-situ measurements since the beginning ...

  6. Plasma transport near material boundaries

    International Nuclear Information System (INIS)

    Singer, C.E.

    1985-06-01

    The fluid theory of two-dimensional (2-d) plasma transport in axisymmetric devices is reviewed. The forces which produce flow across the magnetic field in a collisional plasma are described. These flows may lead to up-down asymmetries in the poloidal rotation and radial fluxes. Emphasis is placed on understanding the conditions under which the known 2-d plasma fluid equations provide a valid description of these processes. Attempts to extend the fluid treatment to less collisional, turbulent plasmas are discussed. A reduction to the 1-d fluid equations used in many computer simulations is possible when sources or boundary conditions provide a large enough radial scale length. The complete 1-d fluid equations are given in the text, and 2-d fluid equations are given in the Appendix

  7. Separation control on curved boundaries

    Science.gov (United States)

    Kamal Kumar, R.; Mathur, Manikandan

    2017-11-01

    Flow separation and its characteristics are an important consideration in the field of bluff body aerodynamics. Specifically, the location and slope of the separation, and the size of the re-circulation bubble that forms downstream of the bluff body significantly affect the resulting aerodynamic forces. Recent theories based on dynamical systems (Haller, 2004) have established criteria based on wall-based quantities that identify the location and slope of separation in unsteady flows. In this work, we adapt the closed-loop separation control algorithm proposed by Alam, Liu & Haller (2006) to curved boundaries, and demonstrate the effectiveness of the same via numerical simulations on the flow past a cylinder in the vortex-shedding regime. Using appropriately placed wall-based actuators that use inputs from shear stress sensors placed between the actuators, we demonstrate that the separation characteristics including the re-circulation bubble length, can be desirably modified.

  8. the Martian atmospheric boundary layer

    DEFF Research Database (Denmark)

    Petrosyan, A.; Galperin, B.; Larsen, Søren Ejling

    2011-01-01

    The planetary boundary layer (PBL) represents the part of the atmosphere that is strongly influenced by the presence of the underlying surface and mediates the key interactions between the atmosphere and the surface. On Mars, this represents the lowest 10 km of the atmosphere during the daytime...... atmosphere. To date, this region of the atmosphere has been studied directly, by instrumented lander spacecraft, and from orbital remote sensing, though not to the extent that is necessary to fully constrain its character and behavior. Current data strongly suggest that as for the Earth's PBL, classical...... of the modeling techniques used for the PBL on Earth are also being applied to the Martian PBL, including novel uses of very high resolution large eddy simulation methods. We conclude with those aspects of the PBL that require new measurements in order to constrain models and discuss the extent to which...

  9. Boundaries of a complex world

    CERN Document Server

    Ludu, Andrei

    2016-01-01

    The central theme of this book is the extent to which the structure of the free dynamical boundaries of a system controls the evolution of the system as a whole. Applying three orthogonal types of thinking - mathematical, constructivist and morphological, it illustrates these concepts using applications to selected problems from the social and life sciences, as well as economics. In a broader context, it introduces and reviews some modern mathematical approaches to the science of complex systems. Standard modeling approaches (based on non-linear differential equations, dynamic systems, graph theory, cellular automata, stochastic processes, or information theory) are suitable for studying local problems. However they cannot simultaneously take into account all the different facets and phenomena of a complex system, and new approaches are required to solve the challenging problem of correlations between phenomena at different levels and hierarchies, their self-organization and memory-evolutive aspects, the grow...

  10. Exploring the magnetospheric boundary layer

    International Nuclear Information System (INIS)

    Hapgood, M.A.; Bryant, D.A.

    1992-01-01

    We show how, for most crossings of the boundary layer, one can construct a 'transition parameter', based on electron density and temperature, which orders independent plasma measurements into well-defined patterns which are consistent from case to case. We conclude that there is a gradual change in the balance of processes which determine the structure of the layer and suggest that there is no advantage in dividing the layer into different regions. We further conclude that the mixing processes in layer act in an organised way to give the consistent patterns revealed by the transition parameter. More active processes must sometimes take to give the extreme values (e.g. in velocity) which are seen in some crossings

  11. Grain boundaries and mechanical properties of nanocrystalline diamond films.

    Energy Technology Data Exchange (ETDEWEB)

    Busmann, H.-G.; Pageler, A.; Gruen, D. M.

    1999-08-06

    Phase-pure nanocrystalline diamond thin films grown from plasmas of a hydrogen-poor carbon argon gas mixture have been analyzed regarding their hardness and elastic moduli by means of a microindentor and a scanning acoustic microscope.The films are superhard and the moduli rival single crystal diamond. In addition, Raman spectroscopy with an excitation wavelength of 1064 nm shows a peak at 1438 l/cm and no peak above 1500 l/cm, and X-ray photoelectron spectroscopy a shake-up loss at 4.2 eV. This gives strong evidence for the existence of solitary double bonds in the films. The hardness and elasticity of the films then are explained by the assumption, that the solitary double bonds interconnect the nanocrystals in the films, leading to an intergrain boundary adhesion of similar strength as the intragrain diamond cohesion. The results are in good agreement with recent simulations of high-energy grain boundaries.

  12. Parallel fast multipole boundary element method applied to computational homogenization

    Science.gov (United States)

    Ptaszny, Jacek

    2018-01-01

    In the present work, a fast multipole boundary element method (FMBEM) and a parallel computer code for 3D elasticity problem is developed and applied to the computational homogenization of a solid containing spherical voids. The system of equation is solved by using the GMRES iterative solver. The boundary of the body is dicretized by using the quadrilateral serendipity elements with an adaptive numerical integration. Operations related to a single GMRES iteration, performed by traversing the corresponding tree structure upwards and downwards, are parallelized by using the OpenMP standard. The assignment of tasks to threads is based on the assumption that the tree nodes at which the moment transformations are initialized can be partitioned into disjoint sets of equal or approximately equal size and assigned to the threads. The achieved speedup as a function of number of threads is examined.

  13. Using Boundary Management for More Effective Product Development

    Directory of Open Access Journals (Sweden)

    John Thomson

    2013-10-01

    Full Text Available Twenty years ago, most companies developed their own products in a single location and brought them to market themselves. Today, original equipment manufacturers (OEMs are enlisting partners on a global scale as subsystem designers and producers in order to create and deliver new products into the market more rapidly and more frequently. This is especially true for large, complex products from the aerospace, telecommunications, electronics, and software industries. To assure the delivery of information across organizational boundaries, new coordination mechanisms need to be adopted (boundary management. In this article, best practices are described on how OEMs and partners self-organize and use agile, cooperative techniques to maintain daily communication among numerous internal and partner engineers to better coordinate product design and system integration. This article focuses on examples from the aerospace industry; however; these tactics can be applied in any organization to innovate at faster rates, to make delivery times more predictable, and to realize shorter product development timelines.

  14. On the Derivation of Boundary Conditions for Continuum Dislocation Dynamics

    Directory of Open Access Journals (Sweden)

    Thomas Hochrainer

    2017-07-01

    Full Text Available Continuum dislocation dynamics (CDD is a single crystal strain gradient plasticity theory based exclusively on the evolution of the dislocation state. Recently, we derived a constitutive theory for the average dislocation velocity in CDD in a phase field-type description for an infinite domain. In the current work, so-called rational thermodynamics is employed to obtain thermodynamically consistent boundary conditions for the dislocation density variables of CDD. We find that rational thermodynamics reproduces the bulk constitutive equations as obtained from irreversible thermodynamics. The boundary conditions we find display strong parallels to the microscopic traction conditions derived by Gurtin and Needleman (M.E. Gurtin and A. Needleman, J. Mech. Phys. Solids 53 (2005 1–31 for strain gradient theories based on the Kröner–Nye tensor.

  15. Boundary layers of the earth's outer magnetosphere

    Science.gov (United States)

    Eastman, T. E.; Frank, L. A.

    1984-01-01

    The magnetospheric boundary layer and the plasma-sheet boundary layer are the primary boundary layers of the earth's outer magnetosphere. Recent satellite observations indicate that they provide for more than 50 percent of the plasma and energy transport in the outer magnetosphere although they constitute less than 5 percent by volume. Relative to the energy density in the source regions, plasma in the magnetospheric boundary layer is predominantly deenergized whereas plasma in the plasma-sheet boundary layer has been accelerated. The reconnection hypothesis continues to provide a useful framework for comparing data sampled in the highly dynamic magnetospheric environment. Observations of 'flux transfer events' and other detailed features near the boundaries have been recently interpreted in terms of nonsteady-state reconnection. Alternative hypotheses are also being investigated. More work needs to be done, both in theory and observation, to determine whether reconnection actually occurs in the magnetosphere and, if so, whether it is important for overall magnetospheric dynamics.

  16. Quantitative Characterization of Boundary Roughness in Metals

    DEFF Research Database (Denmark)

    Sun, Jun

    variable to obtain information of local structural variations such as protrusions and retrusions formed on recrystallization boundaries. The AII value is directionindependent allowing unbiased characterization of morphological irregularities with both closed and non-closed boundary profiles. The length...... structural aspects into account, a detailed characterization is essential of partly recrystallized microstructures focusing on the local shapes of the boundaries, in particular on whether protrusions and retrusions are formed or not. Quantification of the “amount” of boundary roughness in the form...... scale at which the rough features are characterized is determined by a parameter termed sampling radius used to measure the AII values. A number of roughness parameters are developed based on the AII dataset for a boundary or boundary segment, whose local morphological characteristics are represented...

  17. Hamiltonian boundary term and quasilocal energy flux

    International Nuclear Information System (INIS)

    Chen, C.-M.; Nester, James M.; Tung, R.-S.

    2005-01-01

    The Hamiltonian for a gravitating region includes a boundary term which determines not only the quasilocal values but also, via the boundary variation principle, the boundary conditions. Using our covariant Hamiltonian formalism, we found four particular quasilocal energy-momentum boundary term expressions; each corresponds to a physically distinct and geometrically clear boundary condition. Here, from a consideration of the asymptotics, we show how a fundamental Hamiltonian identity naturally leads to the associated quasilocal energy flux expressions. For electromagnetism one of the four is distinguished: the only one which is gauge invariant; it gives the familiar energy density and Poynting flux. For Einstein's general relativity two different boundary condition choices correspond to quasilocal expressions which asymptotically give the ADM energy, the Trautman-Bondi energy and, moreover, an associated energy flux (both outgoing and incoming). Again there is a distinguished expression: the one which is covariant

  18. Absorption boundary conditions for geomertical acoustics

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2012-01-01

    Defining accurate acoustical boundary conditions is of crucial importance for room acoustic simulations. In predicting sound fields using phased geometrical acoustics methods, the absorption coefficients or surface impedances of the boundary surfaces can be used, but no guideline has been developed...... on which boundary condition produces the best results. In this study, various boundary conditions in terms of normal and random incidence absorption coefficients, and normal incidence surface impedances are used in a phased beam tracing model, and simulated results are validated with boundary element...... solutions. Two rectangular rooms with uniform and non-uniform absorption distributions are tested. It is concluded that the impedance and random incidence absorption boundary conditions produce reasonable results with some exceptions at low frequencies for acoustically soft materials....

  19. Quantum walk with one variable absorbing boundary

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feiran [Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, Shaanxi Province, Xi' an Jiaotong University, Xi' an 710049 (China); Department of Applied Physics, School of Science, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Pei, E-mail: zhangpei@mail.ustc.edu.cn [Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, Shaanxi Province, Xi' an Jiaotong University, Xi' an 710049 (China); Department of Applied Physics, School of Science, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Yunlong; Liu, Ruifeng; Gao, Hong; Li, Fuli [Key Laboratory of Quantum Information and Quantum Optoelectronic Devices, Shaanxi Province, Xi' an Jiaotong University, Xi' an 710049 (China); Department of Applied Physics, School of Science, Xi' an Jiaotong University, Xi' an 710049 (China)

    2017-01-15

    Quantum walks constitute a promising ingredient in the research on quantum algorithms; consequently, exploring different types of quantum walks is of great significance for quantum information and quantum computation. In this study, we investigate the progress of quantum walks with a variable absorbing boundary and provide an analytical solution for the escape probability (the probability of a walker that is not absorbed by the boundary). We simulate the behavior of escape probability under different conditions, including the reflection coefficient, boundary location, and initial state. Moreover, it is also meaningful to extend our research to the situation of continuous-time and high-dimensional quantum walks. - Highlights: • A novel scheme about quantum walk with variable boundary is proposed. • The analytical results of the survival probability from the absorbing boundary. • The behavior of survival probability under different boundary conditions. • The influence of different initial coin states on the survival probability.

  20. Grain boundary segregation and intergranular failure

    International Nuclear Information System (INIS)

    White, C.L.

    1980-01-01

    Trace elements and impurities often segregate strongly to grain boundaries in metals and alloys. Concentrations of these elements at grain boundaries are often 10 3 to 10 5 times as great as their overall concentration in the alloy. Because of such segregation, certain trace elements can exert a disproportionate influence on material properties. One frequently observed consequence of trace element segregation to grain boundaries is the occurrence of grain boundary failure and low ductility. Less well known are incidences of improved ductility and inhibition of grain boundary fracture resulting from trace element segregation to grain boundaries in certain systems. An overview of trace element segregation and intergranular failure in a variety of alloy systems as well as preliminary results from studies on Al 3% Li will be presented

  1. Slow Manifolds and Multiple Equilibria in Stratocumulus-Capped Boundary Layers

    Directory of Open Access Journals (Sweden)

    Junya Uchida

    2010-12-01

    Full Text Available In marine stratocumulus-capped boundary layers under strong inversions, the timescale for thermodynamic adjustment is roughly a day, much shorter than the multiday timescale for inversion height adjustment. Slow-manifold analysis is introduced to exploit this timescale separation when boundary layer air columns experience only slow changes in their boundary conditions. Its essence is that the thermodynamic structure of the boundary layer remains approximately slaved to its inversion height and the instantaneous boundary conditions; this slaved structure determines the entrainment rate and hence the slow evolution of the inversion height. Slow-manifold analysis is shown to apply to mixed-layer model and large-eddy simulations of an idealized nocturnal stratocumulus- capped boundary layer; simulations with different initial inversion heights collapse onto single relationships of cloud properties with inversion height. Depending on the initial inversion height, the simulations evolve toward a shallow thin-cloud boundary layer or a deep, well-mixed thick cloud boundary layer. In the large-eddy simulations, these evolutions occur on two separate slow manifolds (one of which becomes unstable if cloud droplet concentration is reduced. Applications to analysis of stratocumulus observations and to pockets of open cells and ship tracks are proposed.

  2. Boundary and initial conditions in protostar calculations

    International Nuclear Information System (INIS)

    Disney, M.J.

    1976-01-01

    On first fragmentation protostars probably form part of a larger protocluster cloud already in a state of dynamic collapse. In that case it is argued that the protostar boundary is initially collapsing at supersonic speed relative to the core. This prevents information from the boundary reaching the core and calls into question models like Larson's, which start homogeneously but become centrally condensed due to the propagation of a rarefaction wave from the boundary. (author)

  3. Reaction diffusion equations with boundary degeneracy

    Directory of Open Access Journals (Sweden)

    Huashui Zhan

    2016-03-01

    Full Text Available In this article, we consider the reaction diffusion equation $$ \\frac{\\partial u}{\\partial t} = \\Delta A(u,\\quad (x,t\\in \\Omega \\times (0,T, $$ with the homogeneous boundary condition. Inspired by the Fichera-Oleinik theory, if the equation is not only strongly degenerate in the interior of $\\Omega$, but also degenerate on the boundary, we show that the solution of the equation is free from any limitation of the boundary condition.

  4. Immersed Boundary-Lattice Boltzmann Method Using Two Relaxation Times

    Directory of Open Access Journals (Sweden)

    Kosuke Hayashi

    2012-06-01

    Full Text Available An immersed boundary-lattice Boltzmann method (IB-LBM using a two-relaxation time model (TRT is proposed. The collision operator in the lattice Boltzmann equation is modeled using two relaxation times. One of them is used to set the fluid viscosity and the other is for numerical stability and accuracy. A direct-forcing method is utilized for treatment of immersed boundary. A multi-direct forcing method is also implemented to precisely satisfy the boundary conditions at the immersed boundary. Circular Couette flows between a stationary cylinder and a rotating cylinder are simulated for validation of the proposed method. The method is also validated through simulations of circular and spherical falling particles. Effects of the functional forms of the direct-forcing term and the smoothed-delta function, which interpolates the fluid velocity to the immersed boundary and distributes the forcing term to fixed Eulerian grid points, are also examined. As a result, the following conclusions are obtained: (1 the proposed method does not cause non-physical velocity distribution in circular Couette flows even at high relaxation times, whereas the single-relaxation time (SRT model causes a large non-physical velocity distortion at a high relaxation time, (2 the multi-direct forcing reduces the errors in the velocity profile of a circular Couette flow at a high relaxation time, (3 the two-point delta function is better than the four-point delta function at low relaxation times, but worse at high relaxation times, (4 the functional form of the direct-forcing term does not affect predictions, and (5 circular and spherical particles falling in liquids are well predicted by using the proposed method both for two-dimensional and three-dimensional cases.

  5. Detonation Shock Dynamics Modelling with Arbitrary Boundaries

    Science.gov (United States)

    Hodgson, Alexander

    2017-06-01

    The Detonation Shock Dynamics (DSD) model can be used to predict detonation wave propagation in a high explosive (HE). The detonation wave is prescribed a velocity that depends on its curvature. Additionally, the angle between the wave and the HE boundary may not exceed a specified ``boundary angle'', the value of which depends on the HE and its confining material(s). The level-set method is commonly used to drive DSD computation. Boundary conditions are applied to the level-set field at the charge edges to maintain the explosive boundary angle criteria. The position of the boundary must be accurate and continuous across adjacent cells to achieve accurate and robust results. This is mainly an issue for mixed material meshes where the boundary does not coincide with the cell boundaries. For such meshes, a set of volume fractions defines the amount of material in each cell. The boundary is defined implicitly by the volume fractions, and must be reconstructed to an explicit form for use in DSD. This work describes a novel synthesis of the level-set method and simulated annealing, an optimisation method used to reconstruct the boundary. The accuracy and robustness of the resulting DSD calculation are evaluated with a range of test problems.

  6. Gauge Fields as Composite Boundary Excitations

    CERN Document Server

    Ferrara, Sergio; Ferrara, Sergio; Fronsdal, Christian

    1998-01-01

    We investigate representations of the conformal group that describe "massless" particles in the interior and at the boundary of anti-de Sitter space. It turns out that massless gauge excitations in anti-de Sitter are gauge "current" operators at the boundary. Conversely, massless excitations at the boundary are topological singletons in the interior. These representations lie at the threshold of two "unitary bounds" that apply to any conformally invariant field theory. Gravity and Yang-Mills gauge symmetry in anti-De Sitter is translated to global translational symmetry and continuous R-symmetry of the boundary superconformal field theory.

  7. Boundary conditions in random sequential adsorption

    Science.gov (United States)

    Cieśla, Michał; Ziff, Robert M.

    2018-04-01

    The influence of different boundary conditions on the density of random packings of disks is studied. Packings are generated using the random sequential adsorption algorithm with three different types of boundary conditions: periodic, open, and wall. It is found that the finite size effects are smallest for periodic boundary conditions, as expected. On the other hand, in the case of open and wall boundaries it is possible to introduce an effective packing size and a constant correction term to significantly improve the packing densities.

  8. Experimental investigation of wave boundary layer

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu

    2003-01-01

    A review is presented of experimental investigation of wave boundary layer. The review is organized in six main sections. The first section describes the wave boundary layer in a real-life environment and its simulation in the laboratory in an oscillating water tunnel and in a water tank...... with an oscillating seabed. A brief account is given of measured quantities, measurement techniques (LDA, PIV, flow visualization) and limitations/constraints in the experimental investigation of the wave boundary layer in the laboratory. The second section concentrates on uniform oscillating boundary layers...

  9. Diffusion mechanisms in grain boundaries in solids

    International Nuclear Information System (INIS)

    Peterson, N.L.

    1982-01-01

    A critical review is given of our current knowledge of grain-boundary diffusion in solids. A pipe mechanism of diffusion based on the well-established dislocation model seems most appropriate for small-angle boundaries. Open channels, which have atomic configurations somewhat like dislocation cores, probably play a major role in large-angle grain-boundary diffusion. Dissociated dislocations and stacking faults are not efficient paths for grain-boundary diffusion. The diffusion and computer modeling experiments are consistent with a vacancy mechanism of diffusion by a rather well-localized vacancy. The effective width of a boundary for grain-boundary diffusion is about two atomic planes. These general features of grain-boundary diffusion, deduced primarily from experiments on metals, are thought to be equally applicable for pure ceramic solids. The ionic character of many ceramic oxides may cause some differences in grain-boundary structure from that observed in metals, resulting in changes in grain-boundary diffusion behavior. 72 references, 5 figures

  10. Comparing Evaluation Metrics for Sentence Boundary Detection

    National Research Council Canada - National Science Library

    Liu, Yang; Shriberg, Elizabeth

    2007-01-01

    .... This paper compares alternative evaluation metrics including the NIST error rate, classification error rate per word boundary, precision and recall, ROC curves, DET curves, precision-recall curves...

  11. From boundaries to boundary work: middle managers creating inter-organizational change.

    Science.gov (United States)

    Oldenhof, Lieke; Stoopendaal, Annemiek; Putters, Kim

    2016-11-21

    Purpose In healthcare, organizational boundaries are often viewed as barriers to change. The purpose of this paper is to show how middle managers create inter-organizational change by doing boundary work: the dual act of redrawing boundaries and coordinating work in new ways. Design/methodology/approach Theoretically, the paper draws on the concept of boundary work from Science and Technology Studies. Empirically, the paper is based on an ethnographic investigation of middle managers that participate in a Dutch reform program across health, social care, and housing. Findings The findings show how middle managers create a sense of urgency for inter-organizational change by emphasizing "fragmented" service provision due to professional, sectoral, financial, and geographical boundaries. Rather than eradicating these boundaries, middle managers change the status quo gradually by redrawing composite boundaries. They use boundary objects and a boundary-transcending vocabulary emphasizing the need for societal gains that go beyond production targets of individual organizations. As a result, work is coordinated in new ways in neighborhood teams and professional expertise is being reconfigured. Research limitations/implications Since boundary workers create incremental change, it is necessary to follow their work for a longer period to assess whether boundary work contributes to paradigm change. Practical implications Organizations should pay attention to conditions for boundary work, such as legitimacy of boundary workers and the availability of boundary spaces that function as communities of practice. Originality/value By shifting the focus from boundaries to boundary work, this paper gives valuable insights into "how" boundaries are redrawn and embodied in objects and language.

  12. Co boundary diffusion in zircon-α grains

    International Nuclear Information System (INIS)

    Corvalan, C; Iribarren, M; Dyment, F

    2006-01-01

    Diffusion in solid state plays a decisive part in most metallurgical processes and, therefore, determining the values of the diffusion coefficients becomes very important. Diffusion in materials in general and in metals in particular occurs because of defects. These can be classified as specific, lineal, bi- and tri-dimensional, and coefficients may be determined for diffusion volume, grain and interphase boundary diffusion, diffusion dislocation, and surface diffusion. A grain boundary (GB) is defined as the region of transition between two adjacent crystals in a single-phase material, which are in contact and only differ in crystallographic orientation. When the transition zone between two grains occurs between two phases of an alloy, it is called interphase boundary (IB). The GB as well as the IB show migration speeds several orders of magnitude greater than those for the volumes of the adjacent regions. At temperatures where the diffusion volume can be considered practically nil, an appreciable although localized amount of material can be displaced along the 'fast-paths'. This implies that not only the diffusion itself, but also the associated phenomena on the grain and interphase boundaries are accelerating. Among these phenomena are: plastic deformation and corrosion at high temperature, stability of precipitates in a synthesized matrix, surface treatments, solid state transformations in general, etc. The experimental determination of the coefficients of diffusion in grain boundaries (GB) and interphase boundaries (IB) yields information about the speeds of migration in the intergranular regions, where important and localized phenomena occur. The B and C kinetics from the Harrison classification are used in this study, which provide reliable results although with some restrictions. This study presents the results of Co diffusion in the GB of pure Zr-α, in the temperature range [430-633] K, with those for C kinetics being the first in this type of material

  13. Turbulence in rough-wall boundary layers: universality issues

    Science.gov (United States)

    Amir, Mohammad; Castro, Ian P.

    2011-08-01

    Wind tunnel measurements of turbulent boundary layers over three-dimensional rough surfaces have been carried out to determine the critical roughness height beyond which the roughness affects the turbulence characteristics of the entire boundary layer. Experiments were performed on three types of surfaces, consisting of an urban type surface with square random height elements, a diamond-pattern wire mesh and a sand-paper type grit. The measurements were carried out over a momentum thickness Reynolds number ( Re θ) range of 1,300-28,000 using two-component Laser Doppler anemometry (LDA) and hot-wire anemometry (HWA). A wide range of the ratio of roughness element height h to boundary layer thickness δ was covered (0.04 ≤ h/δ ≤ 0.40). The results confirm that the mean profiles for all the surfaces collapse well in velocity defect form up to surprisingly large values of h/δ, perhaps as large as 0.2, but with a somewhat larger outer layer wake strength than for smooth-wall flows, as previously found. At lower h/δ, at least up to 0.15, the Reynolds stresses for all surfaces show good agreement throughout the boundary layer, collapsing with smooth-wall results outside the near-wall region. With increasing h/δ, however, the turbulence above the near-wall region is gradually modified until the entire flow is affected. Quadrant analysis confirms that changes in the rough-wall boundary layers certainly exist but are confined to the near-wall region at low h/δ; for h/δ beyond about 0.2 the quadrant events show that the structural changes extend throughout much of the boundary layer. Taken together, the data suggest that above h/δ ≈ 0.15, the details of the roughness have a weak effect on how quickly (with rising h/δ) the turbulence structure in the outer flow ceases to conform to the classical boundary layer behaviour. The present results provide support for Townsend's wall similarity hypothesis at low h/δ and also suggest that a single critical roughness

  14. Louisiana Territorial Boundary, Geographic NAD83, LDOTD (1999) [state_boundary_la_LDOTD_1999

    Data.gov (United States)

    Louisiana Geographic Information Center — The dataset defines the state 'territorial' boundary of Louisiana. The state boundary extends 3 miles out into the Gulf of Mexico from the coastline. This data set...

  15. Boundary Conditions of Methamphetamine Craving

    Science.gov (United States)

    Lopez, Richard B.; Onyemekwu, Chukwudi; Hart, Carl L.; Ochsner, Kevin N.; Kober, Hedy

    2015-01-01

    Methamphetamine use has increased significantly and become a global health concern. Craving is known to predict methamphetamine use and relapse following abstinence. Some have suggested that cravings are automatic, generalized, and uncontrollable, but experimental work addressing these claims is lacking. In two exploratory studies we tested the boundary conditions of methamphetamine craving by asking: (1) is craving specific to users’ preferred route of administration? and (2) can craving be regulated by cognitive strategies? Two groups of methamphetamine users were recruited. In Study 1, participants were grouped by their preferred route of administration (intranasal vs. smoking), and rated their craving in response to photographs and movies depicting methamphetamine use (via the intranasal vs. smoking route). In Study 2, methamphetamine smokers implemented cognitive regulation strategies while viewing photographs depicting methamphetamine smoking. Strategies involved either focusing on the positive aspects of smoking methamphetamine or the negative consequences of doing so – the latter strategy based on treatment protocols for addiction. In Study 1, we found a significant interaction between group and route of administration, such that participants who preferred to smoke methamphetamine reported significantly stronger craving for smoking stimuli, whereas those who preferred the intranasal route reported stronger craving for intranasal stimuli. In Study 2, participants reported significantly lower craving when focusing on the negative consequences associated with methamphetamine use. Taken together, these findings suggest that strength of craving for methamphetamine is moderated by users’ route of administration and can be reduced by cognitive strategies. This has important theoretical, methodological, and clinical implications. PMID:26302338

  16. A note on Weak Stability Boundaries

    OpenAIRE

    García González, Fernando; Gómez Muntané, Gerard

    2006-01-01

    This paper is devoted to clarify the algorithmic definition of the weak stability boundary in the framework of the planar Restricted Three Body Problem. The role of the invariant hyperbolic manifolds associated to the central manifolds of the libration points L1 and L2, as boundary of the weak stability region, is shown Peer Reviewed

  17. Millennial Values and Boundaries in the Classroom

    Science.gov (United States)

    Espinoza, Chip

    2012-01-01

    Students' relationships with authority and information are changing rapidly, and this presents a new set of interpersonal boundary challenges for faculty. The topic of setting boundaries often conjures up thoughts of how to protect oneself. The intent of this chapter is to explore how good rapport between teacher and student can be developed and…

  18. Population models with nonlinear boundary conditions

    Directory of Open Access Journals (Sweden)

    Jerome Goddard

    2010-09-01

    Full Text Available We study a two point boundary-value problem describing the steady states of a Logistic growth population model with diffusion and constant yield harvesting. In particular, we focus on a model when a certain nonlinear boundary condition is satisfied.

  19. Transgressions and Transcendence: Surpassing Disciplinary Boundaries.

    Science.gov (United States)

    Wughalter, Emily H.

    2002-01-01

    Discusses how women such as Amy Morris Homans, Susan B. Anthony, Elizabeth Cady Stanton, and Mary Wollstonecraft transgressed boundaries, allowing others to transcend old boundary limitations in physical education, examining the Boston Normal School of Gymnastics established for training women as directors of physical education over 100 years ago…

  20. Crossing Boundaries in Global Software Development

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    across cultures, languages, organizational boundaries, time zones and geographical distances. The paper revises a framework of boundary spanning leadership practices developed for MNCs and adapts it to an offshore outsourcing context. It also contributes with reflections on how imbalances of resources...

  1. The transactional approach in company boundaries

    Directory of Open Access Journals (Sweden)

    Bruno Chaihuaque Dueñas

    2009-12-01

    Full Text Available This article shows the relationship between market and firms through the theory of transactional cost and the relationsthat determine the structure and boundaries of the firm. Using the assumptions from the transactional cost approach,this article proposes some variables that determine optimal organizational structures and their boundaries.

  2. Modelling stable atmospheric boundary layers over snow

    NARCIS (Netherlands)

    Sterk, H.A.M.

    2015-01-01

    Thesis entitled:

    Modelling Stable Atmospheric Boundary Layers over Snow

    H.A.M. Sterk

    Wageningen, 29th of April, 2015

    Summary

    The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs

  3. Boundary Management for Cognitive Behavioral Therapies

    Science.gov (United States)

    Gottlieb, Michael C.; Younggren, Jeffrey N.; Murch, Kevin B.

    2009-01-01

    In recent years, the scholarship regarding professional boundaries has increased significantly in a variety of areas. Despite many advances in this line of research, less attention has been devoted to the question of boundary maintenance and its relationship to theoretical orientation. In this article we examine these issues for…

  4. Soliton equations solved by the boundary CFT

    OpenAIRE

    Saito, Satoru; Sato, Ryuichi

    2003-01-01

    Soliton equations are derived which characterize the boundary CFT a la Callan et al. Soliton fields of classical soliton equations are shown to appear as a neutral bound state of a pair of soliton fields of BCFT. One soliton amplitude under the influence of the boundary is calculated explicitly and is shown that it is frozen at the Dirichlet limit.

  5. Boundary migration during recrystallization: experimental observations

    DEFF Research Database (Denmark)

    Zhang, Yubin; Juul Jensen, Dorte

    2015-01-01

    Quantitative analysis of boundary migration during recrystallization is a key task to understand the recrystallization process and to improve recrystallization models. In the last 25-30 years, quantification of boundary migration has mostly been conducted in term of average growth rates in many m...

  6. 15 CFR 922.150 - Boundary.

    Science.gov (United States)

    2010-01-01

    ... cutting across the heads of Nitnat, Juan de Fuca and Quinault Canyons. The coastal boundary of the Sanctuary is the mean higher high water line when adjacent to Federally managed lands cutting across the... from the Sanctuary boundary shoreward of the International Collision at Sea regulation (Colreg...

  7. Modelling stable atmospheric boundary layers over snow

    NARCIS (Netherlands)

    Sterk, H.A.M.

    2015-01-01

    Thesis entitled: Modelling Stable Atmospheric Boundary Layers over Snow H.A.M. Sterk Wageningen, 29th of April, 2015 Summary The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs typically form at night and in polar

  8. Hierarchies of DIFFdifference boundary value problems II ...

    African Journals Online (AJOL)

    Hierarchies of DIFFdifference boundary value problems II - applications. ... In particular, we studied the effect of applying a Crum-type transformation to a weighted second order difference equation with general -dependent boundary conditions at the end points, for eigenparameter λ. In this paper we demonstrate by means ...

  9. Professional boundary violations: a literature review.

    Science.gov (United States)

    Manfrin-Ledet, Linda; Porche, Demetrius J; Eymard, Amanda S

    2015-06-01

    The purpose of this article is to review the nursing literature related to professional boundary violations in nursing. A search was conducted using CINAHL, MEDLINE, Ebscohost, and NCSBN. The key words searched were professional boundaries, boundary violation, boundary crossings, nurse, home health nurses, and home nursing. The search returned over 40 publications related specifically to boundary violations and nursing although only four of them are published research studies and one as a dissertation. Seven common characteristics emerged from the nonresearch nursing articles on professional boundaries: (1) Dual relations/role reversal, (2) Gifts and money, (3) Excessive self-disclosure, (4) Secretive behavior, (5) Excessive attention/overinvolvement, (6) Sexual behavior, and (7) Social media. Additional nursing research is greatly needed in the area of professional boundaries. The nurse-patient relationship should always be maintained for the benefit of the patient and not the personal gain of the nurse. Ongoing education in nursing practice regarding professional boundaries is needed. Nurses need to be mindful of state practice acts, codes of conduct, and employer policies.

  10. Prior Information in Inverse Boundary Problems

    DEFF Research Database (Denmark)

    Garde, Henrik

    the change in distinguishability of inclusions (support of an inhomogeneity) as they are placed closer towards the measurement boundary. This is done by determining eigenvalue bounds for differences of pseudodifferential operators on the boundary of the domain. Ultimately, the bounds serves as insight...

  11. Theraputic relationship versus boundary transgressions: Lessons for ...

    African Journals Online (AJOL)

    No therapy exists in a vacuum. It involves striking relationship between the therapists and clients. Such relationships are relationships of trust and are therefore meant to be maintained religiously by adhering strictly to ethnical codes of conduct. However, most times, boundary transgression are inevitable. While boundary ...

  12. Western boundary currents and climate change

    Science.gov (United States)

    Seager, Richard; Simpson, Isla R.

    2016-09-01

    A recent paper in Journal of Geophysical Research-Oceans connects recent changes in atmospheric circulation to poleward movement and intensification of western boundary currents. Causes and characteristics of past and future trends in surface wind stress and western boundary currents are discussed here.

  13. Recent advances in boundary element methods

    CERN Document Server

    Manolis, GD

    2009-01-01

    Addresses the needs of the computational mechanics research community in terms of information on boundary integral equation-based methods and techniques applied to a variety of fields. This book collects both original and review articles on contemporary Boundary Element Methods (BEM) as well as on the Mesh Reduction Methods (MRM).

  14. Classical BV theories on manifolds with boundary

    NARCIS (Netherlands)

    Cattaneo, A.S.; Mnev, P.; Reshetikhin, N.

    2014-01-01

    In this paper we extend the classical BV framework to gauge theories on spacetime manifolds with boundary. In particular, we connect the BV construction in the bulk with the BFV construction on the boundary and we develop its extension to strata of higher codimension in the case of manifolds with

  15. Assessing housing growth when census boundaries change

    Science.gov (United States)

    Alexandra D. Syphard; Susan I. Stewart; Jason McKeefry; Roger B. Hammer; Jeremy S. Fried; Sherry Holcomb; Volker C. Radeloff

    2009-01-01

    The US Census provides the primary source of spatially explicit social data, but changing block boundaries complicate analyses of housing growth over time. We compared procedures for reconciling housing density data between 1990 and 2000 census block boundaries in order to assess the sensitivity of analytical methods to estimates of housing growth in Oregon. Estimates...

  16. Flexibility of Event Boundaries in Autobiographical Memory

    Science.gov (United States)

    Hohman, Timothy J.; Peynircioğlu, Zehra F.; Beason-Held, Lori L.

    2014-01-01

    Events have clear and consistent boundaries that are defined during perception in a manner that influences memory performance. The natural process of event segmentation shapes event definitions during perception, and appears to play a critical role in defining distinct episodic memories at encoding. However, the role of retrieval processes in modifying event definitions is not clear. We explored how such processes changed event boundary definitions at recall. In Experiment 1 we showed that distance from encoding is related to boundary flexibility. Participants were more likely to move self-reported event boundaries to include information reported beyond those boundaries when recalling more distant events compared to more recent events. In Experiment 2, we showed that age also influenced boundary flexibility. Older Age adults were more likely to move event boundaries than College Age adults, and the relationship between distance from encoding and boundary flexibility seen in Experiment 1 was present only in College Age and Middle Age adults. These results suggest that factors at retrieval have a direct impact on event definitions in memory and that, although episodic memories may be initially defined at encoding, these definitions are not necessarily maintained in long-term memory. PMID:22989194

  17. The boundary characteristics of lucid dreamers.

    Science.gov (United States)

    Galvin, F

    1990-06-01

    Based on the previously established personality correlates of frequent lucid dreaming and frequent nightmare dreaming, several hypotheses were generated regarding the boundary characteristics of these dreamers relative to each other and to a control group of non-lucid and comparatively nightmare-free dreamers. The data from Hartmann's Boundary Questionnaire obtained from 40 subjects in each dreamer group (who were individually matched for sex, age, and background as far as possible) were analyzed. The results of the study give evidence that lucid dreamers have "thin" boundaries in many of the same senses that nightmare sufferers do, but can be differentiated from nightmare dreamers by the greater degree of coherence of their psychological sense of self as measured on the Self-Coherence Subscale of the Boundary Questionnaire. The suggestion is made that, given the similarity of "thin" boundaries, perhaps nightmare sufferers could become lucid dreamers and possibly resolve their nightmare condition while in the dream state.

  18. Boundary conditions for the gravitational field

    International Nuclear Information System (INIS)

    Winicour, Jeffrey

    2012-01-01

    A review of the treatment of boundaries in general relativity is presented with the emphasis on application to the formulations of Einstein's equations used in numerical relativity. At present, it is known how to treat boundaries in the harmonic formulation of Einstein's equations and a tetrad formulation of the Einstein-Bianchi system. However, a universal approach valid for other formulations is not in hand. In particular, there is no satisfactory boundary theory for the 3+1 formulations which have been highly successful in binary black hole simulation. I discuss the underlying problems that make the initial-boundary-value problem much more complicated than the Cauchy problem. I review the progress that has been made and the important open questions that remain. Science is a differential equation. Religion is a boundary condition. (Alan Turing, quoted in J D Barrow, 'Theories of Everything') (topical review)

  19. BSLIC: SLIC Superpixels Based on Boundary Term

    Directory of Open Access Journals (Sweden)

    Hai Wang

    2017-02-01

    Full Text Available A modified method for better superpixel generation based on simple linear iterative clustering (SLIC is presented and named BSLIC in this paper. By initializing cluster centers in hexagon distribution and performing k-means clustering in a limited region, the generated superpixels are shaped into regular and compact hexagons. The additional cluster centers are initialized as edge pixels to improve boundary adherence, which is further promoted by incorporating the boundary term into the distance calculation of the k-means clustering. Berkeley Segmentation Dataset BSDS500 is used to qualitatively and quantitatively evaluate the proposed BSLIC method. Experimental results show that BSLIC achieves an excellent compromise between boundary adherence and regularity of size and shape. In comparison with SLIC, the boundary adherence of BSLIC is increased by at most 12.43% for boundary recall and 3.51% for under segmentation error.

  20. Boundary Hamiltonian Theory for Gapped Topological Orders

    Science.gov (United States)

    Hu, Yuting; Wan, Yidun; Wu, Yong-Shi

    2017-06-01

    We report our systematic construction of the lattice Hamiltonian model of topological orders on open surfaces, with explicit boundary terms. We do this mainly for the Levin-Wen string-net model. The full Hamiltonian in our approach yields a topologically protected, gapped energy spectrum, with the corresponding wave functions robust under topology-preserving transformations of the lattice of the system. We explicitly present the wavefunctions of the ground states and boundary elementary excitations. The creation and hopping operators of boundary quasi-particles are constructed. It is found that given a bulk topological order, the gapped boundary conditions are classified by Frobenius algebras in its input data. Emergent topological properties of the ground states and boundary excitations are characterized by (bi-) modules over Frobenius algebras.

  1. Decision Boundary Feature Extraction for Nonparametric Classification

    Science.gov (United States)

    Lee, Chulhee; Landgrebe, David A.

    1993-01-01

    Feature extraction has long been an important topic in pattern recognition. Although many authors have studied feature extraction for parametric classifiers, relatively few feature extraction algorithms are available for nonparametric classifiers. A new feature extraction algorithm based on decision boundaries for nonparametric classifiers is proposed. It is noted that feature extraction for pattern recognition is equivalent to retaining 'discriminantly informative features' and a discriminantly informative feature is related to the decision boundary. Since nonparametric classifiers do not define decision boundaries in analytic form, the decision boundary and normal vectors must be estimated numerically. A procedure to extract discriminantly informative features based on a decision boundary for non-parametric classification is proposed. Experiments show that the proposed algorithm finds effective features for the nonparametric classifier with Parzen density estimation.

  2. The structure and composition of olivine grain boundaries: 40 years of studies, status and current developments

    Science.gov (United States)

    Marquardt, K.; Faul, U. H.

    2018-02-01

    Interfaces in rocks, especially grain boundaries in olivine dominated rocks, have been subject to about 40 years of studies. The grain boundary structure to property relation is fundamental to understand the diverging properties of polycrystalline samples compared to those of single crystals. The number of direct structural observations is small, i.e. in range of 100 micrographs, and the number of measurements of properties directly linked to structural observations is even smaller. Bulk aggregate properties, such as seismic attenuation, rheology and electrical conductivity, are sensitive to grain size, and seem to show influences by grain boundary character distributions. In this context we review previous studies on grain boundary structure and composition and plausible relations to bulk properties. The grain boundary geometry is described using five independent parameters; generally, their structural width ranges between 0.4-1.2 nm and the commonly used 1 nm seems a good approximation. This region of enhanced disorder is often enriched in elements that are incompatible in the perfect crystal lattice. The chemical composition of grain boundaries depends on the bulk rock composition. We determined the 5 parameter grain boundary character distribution (GBCD) for polycrystaline Fo_{90} and studied structure and chemistry at the nm-scale to extend previous measurements. We find that grain boundary planes close to perpendicular to the crystallographic c-direction dominate the grain boundary network. We conclude that linking grain boundary structure in its full geometric parameter space to variations of bulk rock properties is now possible by GBCD determination using EBSD mapping and statistical analyses.

  3. Generation of Boundary Manikin Anthropometry

    Science.gov (United States)

    Young, Karen S.; Margerum, Sarah; Barr, Abbe; Ferrer, Mike A.; Rajulu, Sudhakar

    2008-01-01

    The purpose of this study was to develop 3D digital boundary manikins that are representative of the anthropometry of a unique population. These digital manikins can be used by designers to verify and validate that the components of the spacesuit design satisfy the requirements specified in the Human Systems Integration Requirements (HSIR) document. Currently, the HSIR requires the suit to accommodate the 1st percentile American female to the 99th percentile American male. The manikin anthropometry was derived using two methods: Principal Component Analysis (PCA) and Whole Body Posture Based Analysis (WBPBA). PCA is a statistical method for reducing a multidimensional data set by using eigenvectors and eigenvalues. The goal is to create a reduced data set that encapsulates the majority of the variation in the population. WBPBA is a multivariate analytical approach that was developed by the Anthropometry and Biomechanics Facility (ABF) to identify the extremes of the population for a given body posture. WBPBA is a simulation-based method that finds extremes in a population based on anthropometry and posture whereas PCA is based solely on anthropometry. Both methods yield a list of subjects and their anthropometry from the target population; PCA resulted in 20 female and 22 male subjects anthropometry and WBPBA resulted in 7 subjects' anthropometry representing the extreme subjects in the target population. The subjects anthropometry is then used to 'morph' a baseline digital scan of a person with the same body type to create a 3D digital model that can be used as a tool for designers, the details of which will be discussed in subsequent papers.

  4. Boundary conditions of methamphetamine craving.

    Science.gov (United States)

    Lopez, Richard B; Onyemekwu, Chukwudi; Hart, Carl L; Ochsner, Kevin N; Kober, Hedy

    2015-12-01

    Methamphetamine use has increased significantly and become a global health concern. Craving is known to predict methamphetamine use and relapse following abstinence. Some have suggested that cravings are automatic, generalized, and uncontrollable, but experimental work addressing these claims is lacking. In 2 exploratory studies, we tested the boundary conditions of methamphetamine craving by asking: (a) is craving specific to users' preferred route of administration?, and (b) can craving be regulated by cognitive strategies? Two groups of methamphetamine users were recruited. In Study 1, participants were grouped by their preferred route of administration (intranasal vs. smoking), and rated their craving in response to photographs and movies depicting methamphetamine use (via the intranasal vs. smoking route). In Study 2, methamphetamine smokers implemented cognitive regulation strategies while viewing photographs depicting methamphetamine smoking. Strategies involved either focusing on the positive aspects of smoking methamphetamine or the negative consequences of doing so-the latter strategy based on treatment protocols for addiction. In Study 1, we found a significant interaction between group and route of administration, such that participants who preferred to smoke methamphetamine reported significantly stronger craving for smoking stimuli, whereas those who preferred the intranasal route reported stronger craving for intranasal stimuli. In Study 2, participants reported significantly lower craving when focusing on the negative consequences associated with methamphetamine use. Taken together, these findings suggest that strength of craving for methamphetamine is moderated by users' route of administration and can be reduced by cognitive strategies. This has important theoretical, methodological, and clinical implications. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  5. Dislocation Nucleation on Grain Boundaries: Low Angle Twist and Asymmetric Tilt Boundaries

    Directory of Open Access Journals (Sweden)

    Erman Guleryuz

    2016-07-01

    Full Text Available We investigate the mechanisms of incipient plasticity at low angle twist and asymmetric tilt boundaries in fcc metals. To observe plasticity of grain boundaries independently of the bulk plasticity, we simulate nanoindentation of bicrystals. On the low angle twist boundaries, the intrinsic grain boundary (GB dislocation network deforms under load until a dislocation segment compatible with glide on a lattice slip plane is created. The half loops are then emitted into the bulk of the crystal. Asymmetric twist boundaries considered here did not produce bulk dislocations under load. Instead, the boundary with a low excess volume nucleated a mobile GB dislocation and additional GB defects. The GB sliding proceeded by motion of the mobile GB dislocation. The boundary with a high excess volume sheared elastically, while bulk-nucleated dislocations produced plastic relaxation.

  6. The Role of Grain Boundary Energy on Grain Boundary Complexion Transitions

    Energy Technology Data Exchange (ETDEWEB)

    Bojarski, Stephanie A. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering; Rohrer, Gregory S. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering

    2014-09-01

    Grain boundary complexions are distinct equilibrium structures and compositions of a grain boundary and complexion transformations are transition from a metastable to an equilibrium complexion at a specific thermodynamic and geometric conditions. Previous work indicates that, in the case of doped alumina, a complexion transition that increased the mobility of transformed boundaries and resulted in abnormal grain growth also caused a decrease in the mean relative grain boundary energy as well as an increase in the anisotropy of the grain boundary character distribution (GBCD). The current work will investigate the hypothesis that the rates of complexion transitions that result in abnormal grain growth (AGG) depend on grain boundary character and energy. Furthermore, the current work expands upon this understanding and tests the hypothesis that it is possible to control when and where a complexion transition occurs by controlling the local grain boundary energy distribution.

  7. Grain-Boundary Resistance in Copper Interconnects: From an Atomistic Model to a Neural Network

    Science.gov (United States)

    Valencia, Daniel; Wilson, Evan; Jiang, Zhengping; Valencia-Zapata, Gustavo A.; Wang, Kuang-Chung; Klimeck, Gerhard; Povolotskyi, Michael

    2018-04-01

    Orientation effects on the specific resistance of copper grain boundaries are studied systematically with two different atomistic tight-binding methods. A methodology is developed to model the specific resistance of grain boundaries in the ballistic limit using the embedded atom model, tight- binding methods, and nonequilibrium Green's functions. The methodology is validated against first-principles calculations for thin films with a single coincident grain boundary, with 6.4% deviation in the specific resistance. A statistical ensemble of 600 large, random structures with grains is studied. For structures with three grains, it is found that the distribution of specific resistances is close to normal. Finally, a compact model for grain-boundary-specific resistance is constructed based on a neural network.

  8. Raman spectrum analysis on the solid-liquid boundary layer of BGO crystal growth

    International Nuclear Information System (INIS)

    Zhang Xia; Yin Shaotang; Wan Songming; Zhang Qingli; You Jinglin; Chen Hui; Zhao Sijie

    2007-01-01

    We study the Raman spectra of Bi 4 Ge 3 O 12 crystal at different temperatures, as well as its melt. The structure characters of the single crystal, melt and growth solid-liquid boundary layer of BGO are investigated by their high-temperature Raman spectra for the first time. The rule of structure change of BGO crystal with increasing temperature is analysed. The results show that there exists [GeO 4 ] polyhedral structure and Bi ion independently in BGO melt. The bridge bonds Bi-O-Bi and Bi-O-Ge appear in the crystal and at the boundary layer, but disappear in the melt. The structure of the growth solid-liquid boundary layer is similar to that of BGO crystal. In the melt, the long-range order structure of the crystal disappears. The thickness of the growth solid-liquid boundary layer of BGO crystal is about 50 μm. (authors)

  9. Grain boundary corrosion of copper canister material

    International Nuclear Information System (INIS)

    Fennell, P.A.H.; Graham, A.J.; Smart, N.R.; Sofield, C.J.

    2001-03-01

    The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister. The potential for grain boundary corrosion was investigated by exposing copper specimens, which had undergone different heat treatments and hence had different grain sizes, to aerated artificial bentonite-equilibrated groundwater with two concentrations of chloride, for increasing periods of time. The degree of grain boundary corrosion was determined by atomic force microscopy (AFM) and optical microscopy. AFM showed no increase in grain boundary 'ditching' for low chloride groundwater. In high chloride groundwater the surface was covered uniformly with a fine-grained oxide. No increases in oxide thickness were observed. No significant grain boundary attack was observed using optical microscopy either. The work suggests that in aerated artificial groundwaters containing chloride ions, grain boundary corrosion of copper is unlikely to adversely affect SKB's copper canisters

  10. From affine Hecke algebras to boundary symmetries

    International Nuclear Information System (INIS)

    Doikou, Anastasia

    2005-01-01

    Motivated by earlier works we employ appropriate realizations of the affine Hecke algebra and we recover previously known non-diagonal solutions of the reflection equation for the U q (gl n -bar ) case. The corresponding N site spin chain with open boundary conditions is then constructed and boundary non-local charges associated to the non-diagonal solutions of the reflection equation are derived, as coproduct realizations of the reflection algebra. With the help of linear intertwining relations involving the aforementioned solutions of the reflection equation, the symmetry of the open spin chain with the corresponding boundary conditions is exhibited, being essentially a remnant of the U q (gl n -bar ) algebra. More specifically, we show that representations of certain boundary non-local charges commute with the generators of the affine Hecke algebra and with the local Hamiltonian of the open spin chain for a particular choice of boundary conditions. Furthermore, we are able to show that the transfer matrix of the open spin chain commutes with a certain number of boundary non-local charges, depending on the choice of boundary conditions

  11. Migration mechanisms of a faceted grain boundary

    Science.gov (United States)

    Hadian, R.; Grabowski, B.; Finnis, M. W.; Neugebauer, J.

    2018-04-01

    We report molecular dynamics simulations and their analysis for a mixed tilt and twist grain boundary vicinal to the Σ 7 symmetric tilt boundary of the type {1 2 3 } in aluminum. When minimized in energy at 0 K , a grain boundary of this type exhibits nanofacets that contain kinks. We observe that at higher temperatures of migration simulations, given extended annealing times, it is energetically favorable for these nanofacets to coalesce into a large terrace-facet structure. Therefore, we initiate the simulations from such a structure and study as a function of applied driving force and temperature how the boundary migrates. We find the migration of a faceted boundary can be described in terms of the flow of steps. The migration is dominated at lower driving force by the collective motion of the steps incorporated in the facet, and at higher driving forces by the step detachment from the terrace-facet junction and propagation of steps across the terraces. The velocity of steps on terraces is faster than their velocity when incorporated in the facet, and very much faster than the velocity of the facet profile itself, which is almost stationary. A simple kinetic Monte Carlo model matches the broad kinematic features revealed by the molecular dynamics. Since the mechanisms seem likely to be very general on kinked grain-boundary planes, the step-flow description is a promising approach to more quantitative modeling of general grain boundaries.

  12. Slarti: A boundary condition editor for a coupled climate model

    Science.gov (United States)

    Mickelson, S. A.; Jacob, R. L.; Pierrehumbert, R.

    2006-12-01

    One of the largest barriers to making climate models more flexible is the difficulty in creating new boundary conditions, especially for "deep time" paleoclimate cases where continents are in different positions. Climate models consist of several mutually-interacting component models and the boundary conditions must be consistent between them. We have developed a program called Slarti which uses a Graphical User Interface and a set of consistency rules to aid researchers in creating new, consistent, boundary condition files for the Fast Ocean Atmosphere Model (FOAM). Users can start from existing mask, topography, or bathymetry data or can build a "world" entirely from scratch (e.g. a single island continent). Once a case has been started, users can modify mask, vegetation, bathymetry, topography, and river flow fields by drawing new data through a "paint" interface. Users activate a synchronization button which goes through the fields to eliminate inconsistencies. When the changes are complete and save is selected, Slarti creates all the necessary files for an initial run of FOAM. The data is edited at the highest resolution (the ocean-land surface in FOAM) and then interpolated to the atmosphere resolution. Slarti was implemented in Java to maintain portability across platforms. We also relied heavily on Java Swing components to create the interface. This allowed us to create an object-oriented interface that could be used on many different systems. Since Slarti allows users to visualize their changes, they are able to see areas that may cause problems when the model is ran. Some examples would be lakes from the river flow field and narrow trenches within the bathymetry. Through different checks and options available through its interface, Slarti makes the process of creating new boundary conditions for FOAM easier and faster while reducing the chance for user errors.

  13. COMPARING THE FLOYD AND IDEAL BOUNDARIES OF A METRIC SPACE

    DEFF Research Database (Denmark)

    Buckley, S.M.; Kokkendorff, Simon Lyngby

    2009-01-01

    We discuss and compare the notions of ideal boundaries, Floyd boundaries and Gromov boundaries of metric spaces. The three types of boundaries at infinity are compared in the general setting of unbounded length spaces as well as in the special cases of CAT(0) and Gromov hyperbolic spaces. Gromov...... boundaries, usually defined only for Gromov hyperbolic spaces, are extended to arbitrary metric spaces....

  14. Explicit boundary form factors: The scaling Lee–Yang model

    Energy Technology Data Exchange (ETDEWEB)

    Hollo, L. [MTA Lendület Holographic QFT Group, Wigner Research Centre for Physics, P.O.B. 49, H-1525 Budapest 114 (Hungary); Laczko, Z.B. [Roland Eötvös University, Pázmány Péter sétány 1/A, 1117 Budapest (Hungary); Bajnok, Z. [MTA Lendület Holographic QFT Group, Wigner Research Centre for Physics, P.O.B. 49, H-1525 Budapest 114 (Hungary)

    2014-09-15

    We provide explicit expressions for boundary form factors in the boundary scaling Lee–Yang model for operators with the mildest ultraviolet behavior for all integrable boundary conditions. The form factors of the boundary stress tensor take a determinant form, while the form factors of the boundary primary field contain additional explicit polynomials.

  15. Unsteady Squeezing Flow of Carbon Nanotubes with Convective Boundary Conditions.

    Directory of Open Access Journals (Sweden)

    Tasawar Hayat

    Full Text Available Unsteady flow of nanofluids squeezed between two parallel plates is discussed in the presence of viscous dissipation. Heat transfer phenomenon is disclosed via convective boundary conditions. Carbon nanotubes (single-wall and multi-wall are used as nanoparticles which are homogeneously distributed in the base fluid (water. A system of non-linear differential equations for the flow is obtained by utilizing similarity transformations through the conservation laws. Influence of various emerging parameters on the velocity and temperature profiles are sketched graphically and discussed comprehensively. Analyses of skin fraction coefficient and Nusselt number are also elaborated numerically. It is found out that velocity is smaller for squeezing parameter in the case of multi-wall carbon nanotubes when compared with single-wall carbon nanotubes.

  16. Atom-partitioned multipole expansions for electrostatic potential boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M., E-mail: michael.s.lee131.civ@mail.mil [Simulation Sciences Branch, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Leiter, K. [Simulation Sciences Branch, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Eisner, C. [Secure Mission Solutions, a Parsons Company (United States); Simulation Sciences Branch, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Knap, J. [Simulation Sciences Branch, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States)

    2017-01-01

    Applications such as grid-based real-space density functional theory (DFT) use the Poisson equation to compute electrostatics. However, the expected long tail of the electrostatic potential requires either the use of a large and costly outer domain or Dirichlet boundary conditions estimated via multipole expansion. We find that the oft-used single-center spherical multipole expansion is only appropriate for isotropic mesh domains such as spheres and cubes. In this work, we introduce a method suitable for high aspect ratio meshes whereby the charge density is partitioned into atomic domains and multipoles are computed for each domain. While this approach is moderately more expensive than a single-center expansion, it is numerically stable and still a small fraction of the overall cost of a DFT calculation. The net result is that when high aspect ratio systems are being studied, form-fitted meshes can now be used in lieu of cubic meshes to gain computational speedup.

  17. Crossing Boundaries in Global Software Development

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    activities in a major transformation of a Western client's processes and products? The case study draws on multiple interviews with key boundary spanners in an Indian IT vendor´s on-site and off-shore teams, who are responsible for developing client relations and coordinating complex development projects...... across cultures, languages, organizational boundaries, time zones and geographical distances. The paper revises a framework of boundary spanning leadership practices developed for MNCs and adapts it to an offshore outsourcing context. It also contributes with reflections on how imbalances of resources...

  18. Equation of Motion for a Grain Boundary

    Science.gov (United States)

    Zhang, Luchan; Han, Jian; Xiang, Yang; Srolovitz, David J.

    2017-12-01

    Grain boundary (GB) migration controls many forms of microstructural evolution in polycrystalline materials. Recent theory, simulations, and experiments demonstrate that GB migration is controlled by the motion of discrete line defects or disconnections. We present a continuum equation of motion for grain boundary derived from the underlying discrete disconnection mechanism. We also present an equation of motion for the junctions where multiple grain boundaries meet—as is always the case in a polycrystal. The resulting equation of motion naturally exhibits junction drag—a widely observed phenomena in junction dynamics in solids and liquids.

  19. Identifying Phase Space Boundaries with Voronoi Tessellations

    CERN Document Server

    Debnath, Dipsikha; Kilic, Can; Kim, Doojin; Matchev, Konstantin T.; Yang, Yuan-Pao

    2016-11-24

    Determining the masses of new physics particles appearing in decay chains is an important and longstanding problem in high energy phenomenology. Recently it has been shown that these mass measurements can be improved by utilizing the boundary of the allowed region in the fully differentiable phase space in its full dimensionality. Here we show that the practical challenge of identifying this boundary can be solved using techniques based on the geometric properties of the cells resulting from Voronoi tessellations of the relevant data. The robust detection of such phase space boundaries in the data could also be used to corroborate a new physics discovery based on a cut-and-count analysis.

  20. Optimal Wentzell Boundary Control of Parabolic Equations

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Yousong, E-mail: yousong.luo@rmit.edu.au [RMIT University, School of Mathematical and Geospatial Sciences (Australia)

    2017-04-15

    This paper deals with a class of optimal control problems governed by an initial-boundary value problem of a parabolic equation. The case of semi-linear boundary control is studied where the control is applied to the system via the Wentzell boundary condition. The differentiability of the state variable with respect to the control is established and hence a necessary condition is derived for the optimal solution in the case of both unconstrained and constrained problems. The condition is also sufficient for the unconstrained convex problems. A second order condition is also derived.

  1. Optimal Wentzell Boundary Control of Parabolic Equations

    International Nuclear Information System (INIS)

    Luo, Yousong

    2017-01-01

    This paper deals with a class of optimal control problems governed by an initial-boundary value problem of a parabolic equation. The case of semi-linear boundary control is studied where the control is applied to the system via the Wentzell boundary condition. The differentiability of the state variable with respect to the control is established and hence a necessary condition is derived for the optimal solution in the case of both unconstrained and constrained problems. The condition is also sufficient for the unconstrained convex problems. A second order condition is also derived.

  2. Boundary Value Problems Arising in Kalman Filtering

    Directory of Open Access Journals (Sweden)

    Bashirov Agamirza

    2008-01-01

    Full Text Available The classic Kalman filtering equations for independent and correlated white noises are ordinary differential equations (deterministic or stochastic with the respective initial conditions. Changing the noise processes by taking them to be more realistic wide band noises or delayed white noises creates challenging partial differential equations with initial and boundary conditions. In this paper, we are aimed to give a survey of this connection between Kalman filtering and boundary value problems, bringing them into the attention of mathematicians as well as engineers dealing with Kalman filtering and boundary value problems.

  3. Boundary layer computations using a generalized formulation

    Science.gov (United States)

    Bergeron, D.; Zingg, D. W.

    A numerical solution procedure for a generalized form of the boundary-layer equations based on the formulation of Steger and Van Dalsem is described. The formulation, which is intended for use in a fortified Navier-Stokes procedure, uses the boundary-layer equations expressed in body-confromal coordinates but transformed into generalized coordinates for the solution process. Results are presented for attached and separated transonic airfoil flows with external pressure gradient given from a Navier-Stokes solution in the boundary layers. Discrepancies are noted near shocks and trailing edges, where normal pressure gradients can be appreciable and streamwise velocity gradients can be high.

  4. Boundary value problems and partial differential equations

    CERN Document Server

    Powers, David L

    2005-01-01

    Boundary Value Problems is the leading text on boundary value problems and Fourier series. The author, David Powers, (Clarkson) has written a thorough, theoretical overview of solving boundary value problems involving partial differential equations by the methods of separation of variables. Professors and students agree that the author is a master at creating linear problems that adroitly illustrate the techniques of separation of variables used to solve science and engineering.* CD with animations and graphics of solutions, additional exercises and chapter review questions* Nearly 900 exercises ranging in difficulty* Many fully worked examples

  5. More on boundary holographic Witten diagrams

    Science.gov (United States)

    Sato, Yoshiki

    2018-01-01

    In this paper we discuss geodesic Witten diagrams in general holographic conformal field theories with boundary or defect. In boundary or defect conformal field theory, two-point functions are nontrivial and can be decomposed into conformal blocks in two distinct ways; ambient channel decomposition and boundary channel decomposition. In our previous work [A. Karch and Y. Sato, J. High Energy Phys. 09 (2017) 121., 10.1007/JHEP09(2017)121] we only consider two-point functions of same operators. We generalize our previous work to a situation where operators in two-point functions are different. We obtain two distinct decomposition for two-point functions of different operators.

  6. Cadmium Telluride and Grain Boundaries: A Preliminary Study

    Science.gov (United States)

    Liao, Michael Evan

    The efficacy of the CdCl2 treatment on polycrystalline CdTe-based solar cells was discovered over a quarter of a century ago; and yet, the exact mechanism of this treatment is still not fully understood to this day. In fact, the lack of understanding stems from a debate on the exact role of grain boundaries in CdCl2-treated CdTe solar cells. Some hypothesize that the CdCl2-treatment causes grain boundaries to become beneficial to solar cell performance while others disagree and claim that the treatment simply mitigates the harmful effects of grain boundaries via passivation. A future goal of this project is to determine which, if either, hypothesis is correct by direct wafer bonding single crystalline CdTe. Direct wafer bonding of single crystalline materials would create only one grain boundary at the bonded interface. This approach allows the orientation and surface chemistry of interfaces to be controlled in order to study the chemistry of grain boundaries methodically. However, before any direct wafer bonding can be done, a preliminary study of single crystalline CdTe is necessary. High-quality direct wafer bonding can only be achieved if the surfaces of each wafer satisfy certain requirements. Additionally, analyzing single crystalline CdTe materials prior to bonding is crucial in order to make any insightful connections between results found from direct bonding of single crystalline CdTe and what is observed in polycrystalline CdTe. First, the surface of an (001) CdTe layer epitaxially grown on an (001) InSb substrate is studied using atomic force microscopy. Stacking faults on the CdTe surface are observed and the thickness of the grown CdTe epilayer is calculated by considering the interplanar angles between the (001) and (111) crystallographic planes as well as the dimensions of the stacking faults. While the stacking faults will inhibit successful wafer bonding, the roughness of the regions outside the stacking faults is 0.9 nm, which is an acceptable

  7. The three-dimensional nature of microbands in a channel die compressed Goss-oriented Ni single crystal

    International Nuclear Information System (INIS)

    Afrin, N.; Quadir, M.Z.; Bassman, L.; Driver, J.H.; Albou, A.; Ferry, M.

    2011-01-01

    The three-dimensional structure of microband boundaries in a plane strain compressed Goss-oriented nickel single crystal was generated by the electron backscatter diffraction technique. Rather than being perfectly planar, microband boundaries generally contained bumps and curves. The planar segments of these boundaries have orientations that coincide closely with one of the expected {1 1 1} slip planes of this crystal.

  8. Effects of flow and colony morphology on the thermal boundary layer of corals

    DEFF Research Database (Denmark)

    Jimenez, Isabel M; Kühl, Michael; Larkum, Anthony W D

    2011-01-01

    measurements at the surface of illuminated stony corals with uneven surface topography (Leptastrea purpurea and Platygyra sinensis) revealed millimetre-scale variations in surface temperature and thermal boundary layer (TBL) that may help understand the patchy nature of coral bleaching within single colonies...

  9. How do Economic Crises Impact Firm Boundaries?

    DEFF Research Database (Denmark)

    Foss, Kirsten

    2010-01-01

    How economic crises impact the boundaries of firms has been offered virtually no attention in the literature on the theory of the firm. I review the best-known theories of the firm and identify the variables that matter for the explanation of firm boundaries. I then examine how an economic crisis...... may impact these variables and change efficient firm boundaries. The various theories of the firm have difficulties explaining how firms efficiently adapt their boundaries to such prominent characteristics of economic crisis as declining demand and increased costs of external finance. However, all...... these theories stress uncertainty as an antecedent of firm organization, and as uncertainty is also an important characteristic of an economic crisis I examine how uncertainty is allowed to play out in the various theories in order to identify what predictions we can derive from the theory regarding changes...

  10. Bridging Boundaries in Networked Military Organizations

    NARCIS (Netherlands)

    Kleij, R. van der; Broek, J. van den; Cornelissen, M.; Essens, P.J.D.M.

    2010-01-01

    One of the challenges facing networked military organizations is to coordinate and integrate activities of organization components. Several studies have demonstrated the importance of boundary spanning as integrative mechanism, and, more specifically, individual communication holes within

  11. Combinatorial aspects of boundary loop models

    International Nuclear Information System (INIS)

    Lykke Jacobsen, Jesper; Saleur, Hubert

    2008-01-01

    We discuss in this paper combinatorial aspects of boundary loop models, that is models of self-avoiding loops on a strip where loops get different weights depending on whether they touch the left, the right, both or no boundary. These models are described algebraically by a generalization of the Temperley–Lieb algebra, dubbed the two-boundary TL algebra. We give results for the dimensions of TL representations and the corresponding degeneracies in the partition functions. We interpret these results in terms of fusion and in the light of the recently uncovered A n large symmetry present in loop models, paving the way for the analysis of the conformal field theory properties. Finally, we propose conjectures for determinants of Gram matrices in all cases, including the two-boundary one, which has recently been discussed by de Gier and Nichols

  12. The Community Boundary De-paradoxifyed

    DEFF Research Database (Denmark)

    Dragsdahl Lauritzen, Ghita; Salomo, Søren

    2012-01-01

    participation without a clear distinction of what is part of the community and what is not. This gap is intensified by the emergence of virtual communities, where the notion of boundary is even more distorted. The paper suggests a new construct of virtual community boundaries that sets up the distinction...... between community and its environment differently from existing studies of virtual communities. Instead of taking its starting point in the users, the paper takes an organizational approach and focuses on the function of the community boundary construct. Hereby, the paper shows how community boundaries...... related to user attributes, identity and power produce specific managerial implications that firms must be reflexive about when inviting communities in....

  13. Lubricated immersed boundary method in two dimensions

    Science.gov (United States)

    Fai, Thomas G.; Rycroft, Chris H.

    2018-03-01

    Many biological examples of fluid-structure interaction, including the transit of red blood cells through the narrow slits in the spleen and the intracellular trafficking of vesicles into dendritic spines, involve the near-contact of elastic structures separated by thin layers of fluid. Motivated by such problems, we introduce an immersed boundary method that uses elements of lubrication theory to resolve thin fluid layers between immersed boundaries. We demonstrate 2nd-order accurate convergence for simple two-dimensional flows with known exact solutions to showcase the increased accuracy of this method compared to the standard immersed boundary method. Motivated by the phenomenon of wall-induced migration, we apply the lubricated immersed boundary method to simulate an elastic vesicle near a wall in shear flow. We also simulate the dynamics of a vesicle traveling through a narrow channel and observe the ability of the lubricated method to capture the vesicle motion on relatively coarse fluid grids.

  14. Stellwagen Bank National Marine Sanctuary Boundary (polygon)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of These sanctuaries are...

  15. International Boundary United States Mexico Minute 315

    Data.gov (United States)

    International Boundary & Water Commission — This dataset was created to provide resource managers, public officials, researchers, and the general public with ready access to the location of the international...

  16. National Marine Sanctuary Digital Boundary Files

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of these sanctuaries are...

  17. Allegheny County Pennsylvania Senate District Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the Pennsylvania Senate district boundaries within Allegheny County. If viewing this description on the Western Pennsylvania Regional Data...

  18. Superfund National Priority List (NPL) Site Boundaries

    Data.gov (United States)

    U.S. Environmental Protection Agency — A set of site boundaries for each site in EPA Region 1 (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont) on EPA's Superfund National...

  19. New Mexico HUC-12 Boundaries - 2013

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This data set is a complete digital hydrologic unit boundary layer to the subwatershed (12-digit) 12th level for the State of New Mexico. This data set consists of...

  20. Spanning organizational boundaries to manage creative processes:

    DEFF Research Database (Denmark)

    Andersen, Poul Houman; Kragh, Hanne; Lettl, Christopher

    2013-01-01

    In order to continue to be innovative in the current fast-paced and competitive environment, organizations are increasingly dependent on creative inputs developed outside their boundaries. The paper addresses the boundary spanning activities that managers undertake to a) select and mobilize...... creative talent, b) create shared identity, and c) combine and integrate knowledge in innovation projects involving external actors. We study boundary spanning activities in two creative projects in the LEGO group. One involves identifying and integrating deep, specialized knowledge, the other focuses...... on the use of external actors as a source of broad, not necessarily fully developed ideas. We find that the boundary spanning activities in these two projects differ in respect, among other things, of how the firm selects participants, formulates problems, and aligns the expectations of internal and external...

  1. Boundary Controllability of Nonlinear Fractional Integrodifferential Systems

    Directory of Open Access Journals (Sweden)

    Ahmed HamdyM

    2010-01-01

    Full Text Available Sufficient conditions for boundary controllability of nonlinear fractional integrodifferential systems in Banach space are established. The results are obtained by using fixed point theorems. We also give an application for integropartial differential equations of fractional order.

  2. Boundary Controllability of Integrodifferential Systems in Banach ...

    Indian Academy of Sciences (India)

    Abstract. Sufficient conditions for boundary controllability of integrodifferential systems in Banach spaces are established. The results are obtained by using the strongly continuous semigroup theory and the Banach contraction principle. Examples are provided to illustrate the theory.

  3. EnviroAtlas Community Boundaries Web Service

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the boundaries of all EnviroAtlas Communities. It represents the outside edge of all the block groups included in each EnviroAtlas...

  4. Public Land Survey Township Boundaries of Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This coverage contains polygons representing the PLSS township boundaries of the state of Iowa. TOWNSHIP was developed from a set of 99 individual county coverages...

  5. Boundary layer physics over snow and ice

    Directory of Open Access Journals (Sweden)

    P. S. Anderson

    2008-07-01

    Full Text Available Observations of the unique chemical environment over snow and ice in recent decades, particularly in the polar regions, have stimulated increasing interest in the boundary layer processes that mediate exchanges between the ice/snow interface and the atmosphere. This paper provides a review of the underlying concepts and examples from recent field studies in polar boundary layer meteorology, which will generally apply to atmospheric flow over snow and ice surfaces. It forms a companion paper to the chemistry review papers in this special issue of ACP that focus on processes linking halogens to the depletion of boundary layer ozone in coastal environments, mercury transport and deposition, snow photochemistry, and related snow physics. In this context, observational approaches, stable boundary layer behavior, the effects of a weak or absent diurnal cycle, and transport and mixing over the heterogeneous surfaces characteristic of coastal ocean environments are of particular relevance.

  6. Olympic Coast National Marine Sanctuary Boundary (polygon)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of These sanctuaries are...

  7. Cordell Bank National Marine Sanctuary Boundary (polygon)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of These sanctuaries are...

  8. Florida Keys National Marine Sanctuary Boundary (polygon)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of These sanctuaries are...

  9. State Wildlife Management Area Boundaries - Publicly Accessible

    Data.gov (United States)

    Minnesota Department of Natural Resources — This polygon theme contains boundaries for approximately 1392 Wildlife Management Areas (WMAs) across the state covering nearly 1,288,000 acres. WMAs are part of the...

  10. Monterey Bay National Marine Sanctuary Boundary (polygon)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of These sanctuaries are...

  11. The FSP Boundary Science Driver Plan

    Energy Technology Data Exchange (ETDEWEB)

    Rognlien, T. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Whyte, D. G. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Brooks, J. N. [Purdue Univ., West Lafayette, IN (United States); Canik, J. M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Greenwald, M. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Stotler, D. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Tang, X. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tautges, T. J. [Argonne National Lab. (ANL), Argonne, IL (United States); Wirth, B. D. [Univ. of Tennessee, Knoxville, TN (United States)

    2011-02-18

    This report describes the boundary region in a fusion device. This includes a narrow region where plasma parameters change very rapidly and the near surface of adjoining materials know as plasma-facing components.

  12. Friction stir welding of single crystal aluminium

    DEFF Research Database (Denmark)

    Fonda, Richard Warren; Wert, John A.; Reynolds, A.P.

    2007-01-01

    Friction stir welds were prepared in different orientations in an aluminium single crystal. The welds were quenched to preserve the microstructure surrounding the tool and then electron backscattered diffraction was used to reveal the generation of grain boundaries and the evolution...... to new crystal orientations, producing new grain boundaries in the process. These refined grains develop a {112}. texture closer to the tool. Large conventionally recrystallised grains sometimes form in the outer regions of the refined grain structure, but become ever more deformed as they approach...

  13. International boundary experiences by the United Nations

    Science.gov (United States)

    Kagawa, A.

    2013-12-01

    Over the last few decades, the United Nations (UN) has been approached by Security Council and Member States on international boundary issues. The United Nations regards the adequate delimitation and demarcation of international boundaries as a very important element for the maintenance of peace and security in fragile post-conflict situations, establishment of friendly relationships and cross-border cooperation between States. This paper will present the main principles and framework the United Nations applies to support the process of international boundary delimitation and demarcation activities. The United Nations is involved in international boundary issues following the principle of impartiality and neutrality and its role as mediator. Since international boundary issues are multi-faceted, a range of expertise is required and the United Nations Secretariat is in a good position to provide diverse expertise within the multiple departments. Expertise in different departments ranging from legal, political, technical, administrative and logistical are mobilised in different ways to provide support to Member States depending on their specific needs. This presentation aims to highlight some of the international boundary projects that the United Nations Cartographic Section has been involved in order to provide the technical support to different boundary requirements as each international boundary issue requires specific focus and attention whether it be in preparation, delimitation, demarcation or management. Increasingly, the United Nations is leveraging geospatial technology to facilitate boundary delimitation and demarcation process between Member States. Through the presentation of the various case studies ranging from Iraq - Kuwait, Israel - Lebanon (Blue Line), Eritrea - Ethiopia, Cyprus (Green Line), Cameroon - Nigeria, Sudan - South Sudan, it will illustrate how geospatial technology is increasingly used to carry out the support. In having applied a range

  14. Ferroelectric domain continuity over grain boundaries

    DEFF Research Database (Denmark)

    Mantri, Sukriti; Oddershede, Jette; Damjanovic, Dragan

    2017-01-01

    Formation and mobility of domain walls in ferroelectric materials is responsible for many of their electrical and mechanical properties. Domain wall continuity across grain boundaries has been observed since the 1950's and is speculated to affect the grain boundary-domain interactions, thereby...... techniques in manipulating the micro-structure and domain structure to result in desired interactions between neighbouring grains could prove to be beneficial for future polycrystalline ferroelectric materials....

  15. Dynamics of twin boundaries in martensites

    Energy Technology Data Exchange (ETDEWEB)

    Barsch, G.R.; Horovitz, B.; Krumhansl, J.A.

    1987-09-14

    The theory of forming a coherent twinning array in a parent phase is studied for a tetragonal to orthorhombic displacive transition. We find that this structure can be stabilized without the use of dislocations by a long-range interaction between the twin boundaries which is mediated via the parent phase. The dynamics of the twin boundary lattice consists of elementary excitations with surprisingly low frequency and a limiting -- (wave vector)/sup 1/2/ dispersion.

  16. Knowledge Sharing Across Global-Local Boundaries

    DEFF Research Database (Denmark)

    Zølner, Mette

    The paper explores how locals span boundaries between corporate and local levels. The aim is to better comprehend potentialities and challenges when MNCs draws on locals’ culture specific knowledge. The study is based on an in-depth, interpretive case study of boundary spanning by local actors in...... approach with pattern matching is a way to shed light on the tacit local knowledge that organizational actors cannot articulate and that an exclusively inductive research is not likely to unveil....

  17. Research, Boundaries, and Policy in Networked Learning

    DEFF Research Database (Denmark)

    This book presents cutting-edge, peer reviewed research on networked learning organized by three themes: policy in networked learning, researching networked learning, and boundaries in networked learning. The "policy in networked learning" section explores networked learning in relation to policy...... networks, spaces of algorithmic governance and more. The "boundaries in networked learning" section investigates frameworks of students' digital literacy practices, among other important frameworks in digital learning. Lastly, the "research in networked learning" section delves into new research methods...

  18. Using reciprocity in Boundary Element Calculations

    DEFF Research Database (Denmark)

    Juhl, Peter Møller; Cutanda Henriquez, Vicente

    2010-01-01

    The concept of reciprocity is widely used in both theoretical and experimental work. In Boundary Element calculations reciprocity is sometimes employed in the solution of computationally expensive scattering problems, which sometimes can be more efficiently dealt with when formulated as the recip......The concept of reciprocity is widely used in both theoretical and experimental work. In Boundary Element calculations reciprocity is sometimes employed in the solution of computationally expensive scattering problems, which sometimes can be more efficiently dealt with when formulated...

  19. Boundary layer physics over snow and ice

    OpenAIRE

    Anderson, P. S.; Neff, W. D.

    2008-01-01

    Observations of the unique chemical environment over snow and ice in recent decades, particularly in the polar regions, have stimulated increasing interest in the boundary layer processes that mediate exchanges between the ice/snow interface and the atmosphere. This paper provides a review of the underlying concepts and examples from recent field studies in polar boundary layer meteorology, which will generally apply to atmospheric flow over snow and ice surfaces. It forms a companion paper t...

  20. BUBBLE - an urban boundary layer meteorology project

    DEFF Research Database (Denmark)

    Rotach, M.W.; Vogt, R.; Bernhofer, C.

    2005-01-01

    The Basel urban Boundary Layer Experiment (BUBBLE) was a year-long experimental effort to investigate in detail the boundary layer structure in the City of Basel, Switzerland. At several sites over different surface types (urban, sub-urban and rural reference) towers up to at least twice the main...... a very detailed physical scale-model in a wind tunnel. In the present paper details of all these activities are presented together with first results....

  1. Sierra Nevada Subregional Boundary - Sierra Nevada Conservancy [ds542

    Data.gov (United States)

    California Natural Resource Agency — Sierra Nevada Conservancy (SNC) boundary. The boundary was mapped to correspond with statute AB 2600 (2004) and as re-defined in AB 1201 (2005). Work on the boundary...

  2. DNR Division of Parks and Trails District Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — This data shows the DNR Division of Parks and Trails District Boundaries as of May 2010. The boundaries were created by the Division Leadership Team. Boundaries are...

  3. Sierra Nevada Subregional Boundary - Sierra Nevada Conservancy [ds542

    Data.gov (United States)

    California Department of Resources — Sierra Nevada Conservancy (SNC) boundary. The boundary was mapped to correspond with statute AB 2600 (2004) and as re-defined in AB 1201 (2005). Work on the boundary...

  4. Local boundary migration during recrystallization in pure aluminium

    DEFF Research Database (Denmark)

    Zhang, Yubin; Godfrey, Andrew; Juul Jensen, Dorte

    2011-01-01

    Boundary migration during recrystallization has been followed by an ex situ electron channelling contrast technique, and protrusions/retrusions formed locally on recrystallization boundaries have been quantified. The results show that the motion of recrystallization boundaries is much more complex...

  5. Implementation of Boundary Condition to THALES Code

    International Nuclear Information System (INIS)

    Jang, Beomjun; Chun, Chong Kuk; Park, Ho Young; Woo, Hae-Seuk

    2016-01-01

    The boundary condition of momentum equation of THALES code utilizes the exit pressure boundary to solve the elliptic partial difference momentum equations. This method is the same as the most of the subchannel analysis codes. Other codes such as VIPRE utilize the uniform pressure distribution as outlet boundary condition. In this case, uniform inlet flow rate is assumed. In order to test the core flow field regarding the boundary conditions, analysis was performed for two core conditions. One condition is nominal plant operating condition. In this paper, generic THALES power distribution is used. For nominal operation case, there are no different results depending on the type of outlet pressure boundary condition. But low-power and high-peaking case, density difference for lateral direction becomes large due to high peaking power of core. Since density change causes pressure change, In this case, uniform outlet pressure distribution can't be assumed anymore. Design outlet pressure distribution is measured at nominal core condition. Therefore, design outlet pressure distribution also can't be used due to the difference in core power and flow rate. As a result, it is reasonable that neumann boundary condition is applied in low-power and high peaking core condition including various accident condition

  6. The energetic ion substorm injection boundary

    International Nuclear Information System (INIS)

    Lopez, R.E.; Sibeck, D.G.; McEntire, R.W.; Krimigis, S.M.

    1990-01-01

    The substorm injection boundary model has enjoyed considerable success in explaining plasma signatures in the near-geosynchronous region. However, the injection boundary has remained primarily a phenomenological model. In this paper the authors examine 167 dispersionless energetic ion injections which were observed by AMPTE CCE. The radial and local time distribution of the events as a function of Kp is qualitatively similar to that envisioned in the injection boundary model of Mauk and McIlwain (1974). They argue that particles observed during dispersionless injections are locally energized during the disruption of the cross-tail current sheet. Therefore they identify the injection boundary, as derived from the spatial distribution of dispersionless injections, with the earthward edge of the region of the magnetotail which undergoes current sheet disruption during the substorm expansion phase. The authors show that this qualitative model for the generation of the injection boundary can provide an explanation for the dispersionless nature, the double spiral shape, and the Kp dependence of the boundary

  7. Boundary-layer effects in droplet splashing

    Science.gov (United States)

    Riboux, Guillaume; Gordillo, Jose Manuel

    2017-11-01

    A drop falling onto a solid substrate will disintegrate into smaller parts when its impact velocity exceeds the so called critical velocity for splashing. Under these circumstances, the very thin liquid sheet ejected tangentially to the solid after the drop touches the substrate, lifts off as a consequence of the aerodynamic forces exerted on it and finally breaks into smaller droplets, violently ejected radially outwards, provoking the splash. Here, the tangential deceleration experienced by the fluid entering the thin liquid sheet is investigated making use of boundary layer theory. The velocity component tangent to the solid, computed using potential flow theory provides the far field boundary condition as well as the pressure gradient for the boundary layer equations. The structure of the flow permits to find a self similar solution of the boundary layer equations. This solution is then used to calculate the boundary layer thickness at the root of the lamella as well as the shear stress at the wall. The splash model presented in, which is slightly modified to account for the results obtained from the boundary layer analysis, provides a very good agreement between the measurements and the predicted values of the critical velocity for the splash.

  8. The relationship between grain boundary structure, defect mobility, and grain boundary sink efficiency

    Science.gov (United States)

    Uberuaga, Blas Pedro; Vernon, Louis J.; Martinez, Enrique; Voter, Arthur F.

    2015-01-01

    Nanocrystalline materials have received great attention due to their potential for improved functionality and have been proposed for extreme environments where the interfaces are expected to promote radiation tolerance. However, the precise role of the interfaces in modifying defect behavior is unclear. Using long-time simulations methods, we determine the mobility of defects and defect clusters at grain boundaries in Cu. We find that mobilities vary significantly with boundary structure and cluster size, with larger clusters exhibiting reduced mobility, and that interface sink efficiency depends on the kinetics of defects within the interface via the in-boundary annihilation rate of defects. Thus, sink efficiency is a strong function of defect mobility, which depends on boundary structure, a property that evolves with time. Further, defect mobility at boundaries can be slower than in the bulk, which has general implications for the properties of polycrystalline materials. Finally, we correlate defect energetics with the volumes of atomic sites at the boundary. PMID:25766999

  9. Large eddy simulation of atmospheric boundary layer over wind farms using a prescribed boundary layer approach

    DEFF Research Database (Denmark)

    Chivaee, Hamid Sarlak; Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming

    2012-01-01

    Large eddy simulation (LES) of flow in a wind farm is studied in neutral as well as thermally stratified atmospheric boundary layer (ABL). An approach has been practiced to simulate the flow in a fully developed wind farm boundary layer. The approach is based on the Immersed Boundary Method (IBM......) and involves implementation of an arbitrary prescribed initial boundary layer (See [1]). A prescribed initial boundary layer profile is enforced through the computational domain using body forces to maintain a desired flow field. The body forces are then stored and applied on the domain through the simulation...... and the boundary layer shape will be modified due to the interaction of the turbine wakes and buoyancy contributions. The implemented method is capable of capturing the most important features of wakes of wind farms [1] while having the advantage of resolving the wall layer with a coarser grid than typically...

  10. Study on actinoids in boundary ion transfer from an aspect of solution chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Kihara, Sorin; Shirai, Makoto; Matsui, Masakazu [Kyoto Univ., Uji (Japan). Inst. for Chemical Research; Yoshida, Zenko; Aoyagi, Hisao; Kitatsuji, Yoshihiro

    1996-01-01

    This study aimed to elucidate the fundamental properties of boundary ion transfer between water (W) and organic solvent (O) and to apply the results to the study on actinoid ions. First, dissolved states of ion in W and O in relation to boundary transfer were investigated and the transfer stimulation effects by an addition of some agents which can induce their complex formation were examined. Then, a theoretical equation which expresses a relationship between ion-pair extraction reaction and {Delta}Gtr was proposed and proved with {Delta}Gtr of single ion obtained by the use of VITIES, which is an apparatus for voltammetric determination of boundary ion transfer developed by the authors. Single ion transfer in W/O was estimated from the voltammogram based on I-{Delta}V curve (I; electric current which corresponds to the amount of ion transfer and {Delta}V; phase boundary voltage). In addition, determination of actinoid ion transfer in W/O boundary was made by VITIES to clarify the ion transfer energy, velocity and transferred molecular species. Thus, developments of a new isolation method and a trial sensor for actinoid ions were undertaken based on these results. (M.N.)

  11. Friction and Wear Management Using Solvent Partitioning of Hydrophilic-Surface-Interactive Chemicals Contained in Boundary Layer-Targeted Emulsions

    Science.gov (United States)

    Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor)

    2015-01-01

    Lubrication additives of the current invention require formation of emulsions in base lubricants, created with an aqueous salt solution plus a single-phase compound such that partitioning within the resulting emulsion provides thermodynamically targeted compounds for boundary layer organization thus establishing anti-friction and/or anti-wear. The single-phase compound is termed "boundary layer organizer", abbreviated BLO. These emulsion-contained compounds energetically favor association with tribologic surfaces in accord with the Second Law of Thermodynamics, and will organize boundary layers on those surfaces in ways specific to the chemistry of the salt and BLO additives. In this way friction modifications may be provided by BLOs targeted to boundary layers via emulsions within lubricating fluids, wherein those lubricating fluids may be water-based or oil-based.

  12. Role of Heterochromatin Epigenetic Factors in CML

    Science.gov (United States)

    2008-08-01

    NM_000136.2 FANCC Homo sapiens Fanconi anemia , complementation group C (FANCC), mRNA. 1.07 0.50 0.31 NM_080546.2 SLC44A1 Homo sapiens solute carrier...critical for myeloid differentiation and leading to partial cell de -differentiation, CML acceleration, blast crises and/or secondary acute leukemia

  13. Role of Heterochromatin Epigenetic Factors in CML

    National Research Council Canada - National Science Library

    Grigoryev, Sergei A

    2008-01-01

    .... In specific aim 1 we separated monomeric and high molecular forms of MNEI by chromatography and gel electrophoresis and probed their primary structure by mass spectroscopy and Western blotting...

  14. Boundary Layer Remote Sensing with Combined Active and Passive Techniques: GPS Radio Occultation and High-Resolution Stereo Imaging (WindCam) Small Satellite Concept

    Science.gov (United States)

    Mannucci, A.J.; Wu, D.L.; Teixeira, J.; Ao, C.O.; Xie, F.; Diner, D.J.; Wood, R.; Turk, Joe

    2012-01-01

    Objective: significant progress in understanding low-cloud boundary layer processes. This is the Single largest uncertainty in climate projections. Radio occultation has unique features suited to boundary layer remote sensing (1) Cloud penetrating (2) Very high vertical resolution (approximately 50m-100m) (3) Sensitivity to thermodynamic variables

  15. The effect of boundary slip and cavitation on hydrodynamic pressure generation in pocket bearings

    Science.gov (United States)

    Muchammad, Tauviqirrahman, Mohammad; Pratomo, Ariawan Wahyu; Jamari, J.; Schipper, Dirk J.

    2016-04-01

    Surface texturing as well as boundary slip is an effective approach to increase the tribological performance, friction and load support of lubricated mechanical components. However, in a textured bearing with boundary slip, cavitation, which is generally neglected, is important, and it alters the flow behavior. Therefore, in this paper a novel analytical equation was proposed based on a modified Reynolds equation considering boundary slip and cavitation. The modified Reynolds equation was derived by following the general approach to deduce the Reynolds equation from the Navier-Stokes equation by assuming classical assumptions, except that boundary slip was present. A theoretical investigation was carried out to study the effect of boundary slip including cavitation on the pressure distribution of a pocket bearing. Different slip configurations (full slip, single slip and semi slip) were studied and compared to various pocket depths. The results indicated that the presence of boundary slip both on the leading edge of the contact and the pocket area (i.e. the "semi slip" case) could result in a significant improvement in the hydrodynamic pressure generation; thus, it causes an increased load support. The above improvement depends on the pocket depth of the bearing.

  16. Silicon Σ13(5 0 1) grain boundary interface structure determined by bicrystal Bragg rod X-ray scattering

    International Nuclear Information System (INIS)

    Howes, P.B.; Rhead, S.; Roy, M.; Nicklin, C.L.; Rawle, J.L.; Norris, C.A.

    2013-01-01

    The atomic structure of the silicon Σ13(5 0 1) symmetric tilt grain boundary interface has been determined using Bragg rod X-ray scattering. In contrast to conventional structural studies of grain boundary structure using transmission electron microscopy, this approach allows the non-destructive measurement of macroscopic samples. The interface was found to have a single structure that is fully fourfold coordinated. X-ray diffraction data were measured at Beamline I07 at the Diamond Light Source

  17. High enthalpy hypersonic boundary layer flow

    Science.gov (United States)

    Yanow, G.

    1972-01-01

    A theoretical and experimental study of an ionizing laminar boundary layer formed by a very high enthalpy flow (in excess of 12 eV per atom or 7000 cal/gm) with allowance for the presence of helium driver gas is described. The theoretical investigation has shown that the use of variable transport properties and their respective derivatives is very important in the solution of equilibrium boundary layer equations of high enthalpy flow. The effect of low level helium contamination on the surface heat transfer rate is minimal. The variation of ionization is much smaller in a chemically frozen boundary layer solution than in an equilibrium boundary layer calculation and consequently, the variation of the transport properties in the case of the former was not essential in the integration. The experiments have been conducted in a free piston shock tunnel, and a detailed study of its nozzle operation, including the effects of low levels of helium driver gas contamination has been made. Neither the extreme solutions of an equilibrium nor of a frozen boundary layer will adequately predict surface heat transfer rate in very high enthalpy flows.

  18. An urban approach to planetary boundaries.

    Science.gov (United States)

    Hoornweg, Daniel; Hosseini, Mehdi; Kennedy, Christopher; Behdadi, Azin

    2016-09-01

    The achievement of global sustainable development goals subject to planetary boundaries will mostly be determined by cities as they drive cultures, economies, material use, and waste generation. Locally relevant, applied and quantitative methodologies are critical to capture the complexity of urban infrastructure systems, global inter-connections, and to monitor local and global progress toward sustainability. An urban monitoring (and communications) tool is presented here illustrating that a city-based approach to sustainable development is possible. Following efforts to define and quantify safe planetary boundaries in areas such as climate change, biosphere integrity, and freshwater use, this paper modifies the methodology to propose boundaries from a city's perspective. Socio-economic boundaries, or targets, largely derived from the Sustainable Development Goals are added to bio-physical boundaries. Issues such as data availability, city priorities, and ease of implementation are considered. The framework is trialed for Toronto, Shanghai, Sao Paulo, Mumbai, and Dakar, as well as aggregated for the world's larger cities. The methodology provides an important tool for cities to play a more fulsome and active role in global sustainable development.

  19. Advantageous grain boundaries in iron pnictide superconductors.

    Science.gov (United States)

    Katase, Takayoshi; Ishimaru, Yoshihiro; Tsukamoto, Akira; Hiramatsu, Hidenori; Kamiya, Toshio; Tanabe, Keiichi; Hosono, Hideo

    2011-08-02

    High critical temperature superconductors have zero power consumption and could be used to produce ideal electric power lines. The principal obstacle in fabricating superconducting wires and tapes is grain boundaries-the misalignment of crystalline orientations at grain boundaries, which is unavoidable for polycrystals, largely deteriorates critical current density. Here we report that high critical temperature iron pnictide superconductors have advantages over cuprates with respect to these grain boundary issues. The transport properties through well-defined bicrystal grain boundary junctions with various misorientation angles (θ(GB)) were systematically investigated for cobalt-doped BaFe(2)As(2) (BaFe(2)As(2):Co) epitaxial films fabricated on bicrystal substrates. The critical current density through bicrystal grain boundary (J(c)(BGB)) remained high (>1 MA cm(-2)) and nearly constant up to a critical angle θ(c) of ∼9°, which is substantially larger than the θ(c) of ∼5° for YBa(2)Cu(3)O(7-δ). Even at θ(GB)>θ(c), the decay of J(c)(BGB) was much slower than that of YBa(2)Cu(3)O(7-δ).

  20. Feature Extraction Based on Decision Boundaries

    Science.gov (United States)

    Lee, Chulhee; Landgrebe, David A.

    1993-01-01

    In this paper, a novel approach to feature extraction for classification is proposed based directly on the decision boundaries. We note that feature extraction is equivalent to retaining informative features or eliminating redundant features; thus, the terms 'discriminantly information feature' and 'discriminantly redundant feature' are first defined relative to feature extraction for classification. Next, it is shown how discriminantly redundant features and discriminantly informative features are related to decision boundaries. A novel characteristic of the proposed method arises by noting that usually only a portion of the decision boundary is effective in discriminating between classes, and the concept of the effective decision boundary is therefore introduced. Next, a procedure to extract discriminantly informative features based on a decision boundary is proposed. The proposed feature extraction algorithm has several desirable properties: (1) It predicts the minimum number of features necessary to achieve the same classification accuracy as in the original space for a given pattern recognition problem; and (2) it finds the necessary feature vectors. The proposed algorithm does not deteriorate under the circumstances of equal class means or equal class covariances as some previous algorithms do. Experiments show that the performance of the proposed algorithm compares favorably with those of previous algorithms.

  1. Boundary as Bridge: An Analysis of the Educational Neuroscience Literature from a Boundary Perspective

    Science.gov (United States)

    Beauchamp, Catherine; Beauchamp, Miriam H.

    2013-01-01

    Within the emerging field of educational neuroscience, concerns exist that the impact of neuroscience research on education has been less effective than hoped. In seeking a way forward, it may be useful to consider the problems of integrating two complex fields in the context of disciplinary boundaries. Here, a boundary perspective is used as a…

  2. Existence results for nonlinear boundary-value problems with integral boundary conditions

    Directory of Open Access Journals (Sweden)

    Mouffak Benchohra

    2005-01-01

    Full Text Available In this paper, we investigate the existence of solutions for a second order nonlinear boundary-value problem with integral boundary conditions. By using suitable fixed point theorems, we study the cases when the right hand side has convex and nonconvex values.

  3. A radial distribution function-based open boundary force model for multi-centered molecules

    KAUST Repository

    Neumann, Philipp

    2014-06-01

    We derive an expression for radial distribution function (RDF)-based open boundary forcing for molecules with multiple interaction sites. Due to the high-dimensionality of the molecule configuration space and missing rotational invariance, a computationally cheap, 1D approximation of the arising integral expressions as in the single-centered case is not possible anymore. We propose a simple, yet accurate model invoking standard molecule- and site-based RDFs to approximate the respective integral equation. The new open boundary force model is validated for ethane in different scenarios and shows very good agreement with data from periodic simulations. © World Scientific Publishing Company.

  4. Dissolution kinetics of nanoscale liquid Pb/Bi inclusions at a grain boundary in aluminum

    DEFF Research Database (Denmark)

    Prokofjev, S.I.; Johnson, Erik; Zhilin, V.M.

    2008-01-01

    . Dissolution of the inclusions was observed until their complete disappearance. Digitized video recordings of the process of dissolution were used to obtain the dependence of the inclusion size with time. The kinetics of the dissolution of the grain boundary inclusions can be described with a model where......In situ transmission electron microscopy is used to study dissolution of liquid single-phase Pb/Bi inclusions attached to a grain boundary in an alloy of Al99.29Pb0.65Bi0.06 at temperatures of 343, 370, and 389 degrees C, respectively. The initial size of the inclusions was smaller than 60 nm...

  5. Modeling and analysis of unsteady axisymmetric squeezing fluid flow through porous medium channel with slip boundary.

    Science.gov (United States)

    Qayyum, Mubashir; Khan, Hamid; Rahim, M Tariq; Ullah, Inayat

    2015-01-01

    The aim of this article is to model and analyze an unsteady axisymmetric flow of non-conducting, Newtonian fluid squeezed between two circular plates passing through porous medium channel with slip boundary condition. A single fourth order nonlinear ordinary differential equation is obtained using similarity transformation. The resulting boundary value problem is solved using Homotopy Perturbation Method (HPM) and fourth order Explicit Runge Kutta Method (RK4). Convergence of HPM solution is verified by obtaining various order approximate solutions along with absolute residuals. Validity of HPM solution is confirmed by comparing analytical and numerical solutions. Furthermore, the effects of various dimensionless parameters on the longitudinal and normal velocity profiles are studied graphically.

  6. Analysis of Unsteady Axisymmetric Squeezing Fluid Flow with Slip and No-Slip Boundaries Using OHAM

    Directory of Open Access Journals (Sweden)

    Mubashir Qayyum

    2015-01-01

    Full Text Available In this manuscript, An unsteady axisymmetric flow of nonconducting, Newtonian fluid squeezed between two circular plates is studied with slip and no-slip boundaries. Using similarity transformation, the system of nonlinear partial differential equations is reduced to a single fourth order ordinary differential equation. The resulting boundary value problems are solved by optimal homotopy asymptotic method (OHAM and fourth order explicit Runge-Kutta method (RK4. It is observed that the results obtained from OHAM are in good agreement with numerical results by means of residuals. Furthermore, the effects of various dimensionless parameters on the velocity profiles are investigated graphically.

  7. Investigation of the role of grain boundary on the mechanical properties of metals

    International Nuclear Information System (INIS)

    Kheradmand, Nousha; Barnoush, Afrooz; Vehoff, Horst

    2010-01-01

    Compression testing of micropillars was used to investigate the gain boundary effect on the strength of metals which is especially interesting in ultra fine grained and nanocrystalline metals. Single and bicrystal micropillars of different sizes and crystallographic orientations were fabricated using a focused ion beam system and the compression test was performed with a nanoindenter. A reduction of the pillar size as well as the introduction of a grain boundary results in an increase in the yield strength. The results show that the size and the orientation of different adjoining crystals in bicrystalline pillars have an obvious effect on dislocation nucleation and multiplication.

  8. Infinite-Dimensional Boundary Observer for Lithium-Ion Battery State Estimation

    DEFF Research Database (Denmark)

    Hasan, Agus; Jouffroy, Jerome

    2017-01-01

    This paper presents boundary observer design for state-of-charge (SOC) estimation of lithium-ion batteries. The lithium-ion battery dynamics are governed by thermal-electrochemical principles, which mathematically modeled by partial differential equations (PDEs). In general, the model is a reaction......-diffusion equation with time-dependent coefficients. A Luenberger observer is developed using infinite-dimensional backstepping method and uses only a single measurement at the boundary of the battery. The observer gains are computed by solving the observer kernel equation. A numerical example is performed to show...

  9. Interorganizational Boundary Spanning in Global Software Development

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    projects across multiple cultures, languages, organisational boundaries, time zones and geographical distances. It looks into how these vendor managers get prepared for their complex boundary spanning work, which cross-cultural challenges they experience in their collaboration with Western clients...... to virtuality and cultural diversity. This paper, which draws on a case study of collaborative work in a global software development project, focuses on key boundary spanners in an Indian vendor company, who are responsible for developing trustful and sustainable client relations and coordinating complex...... (economic, cultural, social and symbolic) in the analysis of imbalances of power between the vendor and the client, they highlight that power and politics need to be taken into account when studying collaborative partnerships in a global context....

  10. Using reciprocity in Boundary Element Calculations

    DEFF Research Database (Denmark)

    Juhl, Peter Møller; Cutanda Henriquez, Vicente

    2010-01-01

    The concept of reciprocity is widely used in both theoretical and experimental work. In Boundary Element calculations reciprocity is sometimes employed in the solution of computationally expensive scattering problems, which sometimes can be more efficiently dealt with when formulated as the recip......The concept of reciprocity is widely used in both theoretical and experimental work. In Boundary Element calculations reciprocity is sometimes employed in the solution of computationally expensive scattering problems, which sometimes can be more efficiently dealt with when formulated...... as the reciprocal radiation problem. The present paper concerns the situation of having a point source (which is reciprocal to a point receiver) at or near a discretized boundary element surface. The accuracy of the original and the reciprocal problem is compared in a test case for which an analytical solution...

  11. An Architecture For Boundary-Based Segmentation

    Science.gov (United States)

    Adffel, J. M.; Sanz, J. L. C.; Jain, A. K.; Current, K. W.

    1988-02-01

    A novel hardware architecture for extracting region boundaries in two raster scan passes through a binary image is presented. The first pass gathers statistics regarding the size of each object contour. This information is used to dynamically allocate available memory for storage of boundary codes. In the second raster pass, the same architecture constructs lists of Grid-Joint Codes to represent the perimeter pixels of each object. These codes, referred to variously as "crack" codes or "raster-chain" codes in the literature, are later decoded by the hardware to reproduce the ordered sequence of coordinates surrounding each object. This list of coordinates is useful for the variety of shape recognition and manipulation algorithms which utilize boundary information. We present results of software simulations of the VLSI architecture, along with measurements of the coding efficiency of the basic algorithm, and estimates of the overall chip complexity.

  12. Exponential Boundary Observers for Pressurized Water Pipe

    Science.gov (United States)

    Hermine Som, Idellette Judith; Cocquempot, Vincent; Aitouche, Abdel

    2015-11-01

    This paper deals with state estimation on a pressurized water pipe modeled by nonlinear coupled distributed hyperbolic equations for non-conservative laws with three known boundary measures. Our objective is to estimate the fourth boundary variable, which will be useful for leakage detection. Two approaches are studied. Firstly, the distributed hyperbolic equations are discretized through a finite-difference scheme. By using the Lipschitz property of the nonlinear term and a Lyapunov function, the exponential stability of the estimation error is proven by solving Linear Matrix Inequalities (LMIs). Secondly, the distributed hyperbolic system is preserved for state estimation. After state transformations, a Luenberger-like PDE boundary observer based on backstepping mathematical tools is proposed. An exponential Lyapunov function is used to prove the stability of the resulted estimation error. The performance of the two observers are shown on a water pipe prototype simulated example.

  13. Fourier analysis and boundary value problems

    CERN Document Server

    Gonzalez-Velasco, Enrique A

    1996-01-01

    Fourier Analysis and Boundary Value Problems provides a thorough examination of both the theory and applications of partial differential equations and the Fourier and Laplace methods for their solutions. Boundary value problems, including the heat and wave equations, are integrated throughout the book. Written from a historical perspective with extensive biographical coverage of pioneers in the field, the book emphasizes the important role played by partial differential equations in engineering and physics. In addition, the author demonstrates how efforts to deal with these problems have lead to wonderfully significant developments in mathematics.A clear and complete text with more than 500 exercises, Fourier Analysis and Boundary Value Problems is a good introduction and a valuable resource for those in the field.Key Features* Topics are covered from a historical perspective with biographical information on key contributors to the field* The text contains more than 500 exercises* Includes practical applicati...

  14. Accelerating search kinetics by following boundaries

    Science.gov (United States)

    Calandre, T.; Bénichou, O.; Voituriez, R.

    2014-06-01

    We derive exact expressions of the mean first-passage time to a bulk target for a random searcher that performs boundary-mediated diffusion in a circular domain. Although nonintuitive for bulk targets, it is found that boundary excursions, if fast enough, can minimize the search time. A scaling analysis generalizes these findings to domains of arbitrary shapes and underlines their robustness. Overall, these results provide a generic mechanism of optimization of search kinetics in interfacial systems, which could have important implications in chemical physics. In the context of animal behavior sciences, it shows that following the boundaries of a domain can accelerate a search process, and therefore suggests that thigmotactism could be a kinetically efficient behavior.

  15. A Boundary Property for Upper Domination

    KAUST Repository

    AbouEisha, Hassan M.

    2016-08-08

    An upper dominating set in a graph is a minimal (with respect to set inclusion) dominating set of maximum cardinality.The problem of finding an upper dominating set is generally NP-hard, but can be solved in polynomial time in some restricted graph classes, such as P4-free graphs or 2K2-free graphs.For classes defined by finitely many forbidden induced subgraphs, the boundary separating difficult instances of the problem from polynomially solvable ones consists of the so called boundary classes.However, none of such classes has been identified so far for the upper dominating set problem.In the present paper, we discover the first boundary class for this problem.

  16. Deconvolution estimation of mixture distributions with boundaries

    Science.gov (United States)

    Lee, Mihee; Hall, Peter; Shen, Haipeng; Marron, J. S.; Tolle, Jon; Burch, Christina

    2013-01-01

    In this paper, motivated by an important problem in evolutionary biology, we develop two sieve type estimators for distributions that are mixtures of a finite number of discrete atoms and continuous distributions under the framework of measurement error models. While there is a large literature on deconvolution problems, only two articles have previously addressed the problem taken up in our article, and they use relatively standard Fourier deconvolution. As a result the estimators suggested in those two articles are degraded seriously by boundary effects and negativity. A major contribution of our article is correct handling of boundary effects; our method is asymptotically unbiased at the boundaries, and also is guaranteed to be nonnegative. We use roughness penalization to improve the smoothness of the resulting estimator and reduce the estimation variance. We illustrate the performance of the proposed estimators via our real driving application in evolutionary biology and two simulation studies. Furthermore, we establish asymptotic properties of the proposed estimators. PMID:24009793

  17. Casimir pistons with general boundary conditions

    Directory of Open Access Journals (Sweden)

    Guglielmo Fucci

    2015-02-01

    Full Text Available In this work we analyze the Casimir energy and force for a scalar field endowed with general self-adjoint boundary conditions propagating in a higher dimensional piston configuration. The piston is constructed as a direct product I×N, with I=[0,L]⊂R and N a smooth, compact Riemannian manifold with or without boundary. The study of the Casimir energy and force for this configuration is performed by employing the spectral zeta function regularization technique. The obtained analytic results depend explicitly on the spectral zeta function associated with the manifold N and the parameters describing the general boundary conditions imposed. These results are then specialized to the case in which the manifold N is a d-dimensional sphere.

  18. Grain boundary disordering just before partial melting

    Science.gov (United States)

    Takei, Y.

    2017-12-01

    Recent experimental studies by using a rock analogue (organic polycrystals) have shown that significant enhancement of anelastic relaxation and steady-state creep in the partially molten aggregates starts from considerably below the solidus temperature in the absence of melt (Takei et al, 2014; Yamauchi & Takei, 2016, JGR). These results suggest that melt is not necessary to explain the seismic low velocity, high attenuation, and weak viscosity regions in the upper mantle. Indeed, Priestley & McKenzie (2006, 2013, EPSL) captured a steep reduction of seismic Vs just below the dry peridotite solidus, which was explained well by the empirical model of Yamauchi & Takei (2016). In spite of many geophysical implications (Takei, 2017, Ann. Rev. EPS, in press), however, underlying physics for the mechanical weakening just before partial melting remains unclear. The purpose of this study is to develop a physical model. Anelasticity and viscosity measured by Yamauchi & Takei (2016) are both rate-controlled by grain-boundary diffusion. Therefore, their observations suggest that the dynamic properties of grain boundary change just before partial melting. Significant disordering of grain boundary just before partial melting has been predicted theoretically in the area of material sciences (sometimes called `pre-melting'). I will summarize the thermodynamic models of grain boundary developed in these studies, and compare the predictions of these models to the experimental observations by Yamauchi & Takei (2016). Using these models, I will also clarify a relationship between grain-boundary disordering and grain-boundary wetting, and a different behavior between pure and binary systems in pre-melting. Acknowledgement: I thank R. Cooper for letting me know about the theoretical studies of pre-melting in binary eutectic system.

  19. The Ocean Boundary Layer beneath Hurricane Frances

    Science.gov (United States)

    Dasaro, E. A.; Sanford, T. B.; Terrill, E.; Price, J.

    2006-12-01

    The upper ocean beneath the peak winds of Hurricane Frances (57 m/s) was measured using several varieties of air-deployed floats as part of CBLAST. A multilayer structure was observed as the boundary layer deepened from 20m to 120m in about 12 hours. Bubbles generated by breaking waves create a 10m thick surface layer with a density anomaly, due to the bubbles, of about 1 kg/m3. This acts to lubricate the near surface layer. A turbulent boundary layer extends beneath this to about 40 m depth. This is characterized by large turbulent eddies spanning the boundary layer. A stratified boundary layer grows beneath this reaching 120m depth. This is characterized by a gradient Richardson number of 1/4, which is maintained by strong inertial currents generated by the hurricane, and smaller turbulent eddies driven by the shear instead of the wind and waves. There is little evidence of mixing beneath this layer. Heat budgets reveal the boundary layer to be nearly one dimensional through much of the deepening, with horizontal and vertical heat advection becoming important only after the storm had passed. Turbulent kinetic energy measurements support the idea of reduced surface drag at high wind speeds. The PWP model correctly predicts the degree of mixed layer deepening if the surface drag is reduced at high wind speed. Overall, the greatest uncertainty in understanding the ocean boundary layer at these extreme wind speeds is a characterization of the near- surface processes which govern the air-sea fluxes and surface wave properties.

  20. Introduction: Working the Boundaries of Law

    Directory of Open Access Journals (Sweden)

    Morag McDermont

    2017-12-01

    Full Text Available This introduction to the special issue on Working the Boundaries of Law provides a context for the papers collected here. It locates the papers in a colloquium held in Oñati to discuss issues around this theme. It traces the significance of borders and boundaries as sites of social practice and considers how the boundaries of law are constructed and contested. The introduction then explores the sorts of practices – or labour – that go on at these boundaries – to maintain, challenge and traverse them. It points in particular to boundaries as sites of translation and emotional labour. Finally, it briefly introduces the papers that follow. Esta introducción al número especial Working the Boundaries of Law proporciona un contexto para los artículos que forman el número. Ubica los artículos en un coloquio que tuvo lugar en Oñati para debatir asuntos relacionados con el tema principal. Rastrea el significado de los límites y las fronteras como lugares de práctica social, y considera cómo se construyen y se contestan los límites de la legalidad. Después, esta introducción explora el tipo de prácticas -o trabajos- que suceden en estos límites -para mantenerlos, desafiarlos y atravesarlos. En particular, apunta a los límites como lugares de conversión y de gestión de las emociones. Por último, presenta brevemente los artículos que siguen. DOWNLOAD THIS PAPER FROM SSRN: http://ssrn.com/abstract=3062565

  1. Boundary control of fluid flow through porous media

    DEFF Research Database (Denmark)

    Hasan, Agus; Foss, Bjarne; Sagatun, Svein Ivar

    2010-01-01

    The flow of fluids through porous media can be described by the Boussinesq’s equation with mixed boundary conditions; a Neumann’s boundary condition and a nonlinear boundary condition. The nonlinear boundary condition provides a means to control the fluid flow through porous media. In this paper...

  2. On the solvability of initial boundary value problems for nonlinear ...

    African Journals Online (AJOL)

    In this paper, we study the initial boundary value problems for a non-linear time dependent Schrödinger equation with Dirichlet and Neumann boundary conditions, respectively. We prove the existence and uniqueness of solutions of the initial boundary value problems by using Galerkin's method. Keywords: Initial boundary ...

  3. An Exploration of Boundaries and Solidarity in Counseling Relationships

    Science.gov (United States)

    Speight, Suzette L.

    2012-01-01

    This article explores the boundaries between clinicians and clients in light of the construct of solidarity. A universal conception of boundaries is critiqued and a culturally congruent view of boundaries is examined, rooted in the concept of solidarity. The article includes case illustrations of the connection between boundaries and solidarity…

  4. Boundary organizations to boundary chains: Prospects for advancing climate science application

    Directory of Open Access Journals (Sweden)

    Christine J. Kirchhoff

    2015-01-01

    Full Text Available Adapting to climate change requires the production and use of climate information to inform adaptation decisions. By facilitating sustained interaction between science producers, boundary organizations narrow the gap between science and decision-making and foster the co-production of actionable knowledge. While traditional boundary organization approaches focused on intense one-on-one interactions between producers and users increases usability, this approach requires significant time and resources. Forming “boundary chains”, linking complimentary boundary organizations together, may reduce those costs. In this paper, we use longitudinal observations of a boundary chain, interviews and surveys to explore: (1 how producer-user interactions increase understanding and information usability and (2 if and how efficiencies in climate information production, dissemination and use arise as a result of the boundary chain. We find that forming and sustaining an effective boundary chain requires not only interest, commitment and investment from every link in the chain but also a level of non-overlapping mutual dependency and complementary skill sets. In this case, GLISA’s strength in producing scientific information and their credibility as climate scientists and HRWC’s strengths in facilitation, connection with potential information users, and their recognition and reputation in the watershed add value to the boundary chain enabling the boundary chain to accomplish more with greater efficiency than if each organization in the chain tried to work independently. Finally, data show how the boundary chain increased efficiencies in educating potential users about the strengths and limitations of climate science and improving the production, dissemination, and use of climate information.

  5. Boundary Spanning in Global Software Development

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    How does a global company deal with inter-organizational boundary spanning activities? If the company is an Indian vendor, and the client a Western multinational company in need of major transformations, the answer to this question challenges prior research. This paper builds on a field study...... of Indian IT vendor managers who are responsible for developing client relations and coordinating complex global development projects. The authors revise a framework of boundary spanning leadership practices to adapt it to an offshore outsourcing context. The empirical investigation highlights how...

  6. Bursting frequency prediction in turbulent boundary layers

    Energy Technology Data Exchange (ETDEWEB)

    LIOU,WILLIAM W.; FANG,YICHUNG

    2000-02-01

    The frequencies of the bursting events associated with the streamwise coherent structures of spatially developing incompressible turbulent boundary layers were predicted using global numerical solution of the Orr-Sommerfeld and the vertical vorticity equations of hydrodynamic stability problems. The structures were modeled as wavelike disturbances associated with the turbulent mean flow. The global method developed here involves the use of second and fourth order accurate finite difference formula for the differential equations as well as the boundary conditions. An automated prediction tool, BURFIT, was developed. The predicted resonance frequencies were found to agree very well with previous results using a local shooting technique and measured data.

  7. The Organizational Blog as a Boundary Object

    DEFF Research Database (Denmark)

    Agerdal-Hjermind, Annette

    2012-01-01

    This article looks at organizational blogger roles and how they both reflect and affect the way knowledge is communicated across department boundaries in a corporate blogging context. The blog is approached from a sociotechnical perspective, addressing and looking into the various roles in a comm......This article looks at organizational blogger roles and how they both reflect and affect the way knowledge is communicated across department boundaries in a corporate blogging context. The blog is approached from a sociotechnical perspective, addressing and looking into the various roles...

  8. Fractal boundaries in chaotic hamiltonian systems

    Science.gov (United States)

    Viana, R. L.; Mathias, A. C.; Marcus, F. A.; Kroetz, T.; Caldas, I. L.

    2017-10-01

    Fractal structures are typically present in the dynamics of chaotic orbits in non-integrable open Hamiltonian systems and result from the extremely complicated nature of the invariant manifolds of unstable periodic orbits. Exit basins, the set of initial conditions leading to orbits escaping through a given exit, have very frequently fractal boundaries. In this work we analyze exit basin boundaries in a dynamical system of physical interest, namely the motion of charged particles in a magnetized plasma subjected to electrostatic drift waves, and characterize in a quantitative way the fractality of these structures and their observable consequences, as the final-state uncertainty.

  9. The Boundary Layer in compact binaries

    OpenAIRE

    Hertfelder, Marius; Kley, Wilhelm; Suleimanov, Valery; Werner, Klaus

    2013-01-01

    Disk accretion onto stars leads to the formation of a Boundary Layer (BL) near the stellar surface where the disk makes contact with the star. Albeit a large fraction of the total luminosity of the system originates from this tiny layer connecting the accretion disk and the accreting object, its structure has not been fully understood yet. It is the aim of this work, to obtain more insight into the Boundary Layer around the white dwarf in compact binary systems. There are still many uncertain...

  10. Effective Field Theory on Manifolds with Boundary

    Science.gov (United States)

    Albert, Benjamin I.

    In the monograph Renormalization and Effective Field Theory, Costello made two major advances in rigorous quantum field theory. Firstly, he gave an inductive position space renormalization procedure for constructing an effective field theory that is based on heat kernel regularization of the propagator. Secondly, he gave a rigorous formulation of quantum gauge theory within effective field theory that makes use of the BV formalism. In this work, we extend Costello's renormalization procedure to a class of manifolds with boundary and make preliminary steps towards extending his formulation of gauge theory to manifolds with boundary. In addition, we reorganize the presentation of the preexisting material, filling in details and strengthening the results.

  11. Platinum group element enrichments and possible chondritic Ru:Ir across the Frasnian-Famennian boundary, western New York State.

    Science.gov (United States)

    Over, D J; Conaway, C A; Katz, D J; Goodfellow, W D; Gregoire, D C

    1997-08-01

    The Frasnian-Famennian boundary is recognized as the culmination of a global mass extinction in the Late Devonian. In western New York State the boundary is a distinct horizon within a pyritic black shale bed of the upper Hanover Shale defined by the first occurrence of Palmatolepis triangularis in the absence of Frasnian conodonts. The boundary is characterized by a minor disconformity marked by a lag concentration of conodonts. Iridium at the boundary is 0.11-0.24 ng/g, two to five times background levels of <0.05 ng/g; other Ir enrichments of 0.38 ng/g and 0.49 ng/g occur within 50 cm of the conodont-constrained boundary. Numerous Ir enrichments in the boundary interval suggest extraterrestrial accretion and platinum group element (PGE) concentration at disconformities, or mobilization and concentration in organic-rich/pyritic-rich laminations from cosmic or terrestrial sources. PGE ratios of Pt/Pd and Ku/Ir at the boundary horizon approximate chondritic ratios and are suggestive of an unaltered extraterrestrial source. These values do not conclusively establish a single extraterrestrial impact as the ultimate cause of the Frasnian-Famennian mass extinction, especially given the presence of similar Ir enrichments elsewhere in the section and the absence at the boundary of microtektites and shocked mineral grains.

  12. Role of SUPERMAN in maintaining Arabidopsis floral whorl boundaries.

    Science.gov (United States)

    Sakai, H; Medrano, L J; Meyerowitz, E M

    1995-11-09

    The Arabidopsis gene SUPERMAN (SUP) is necessary for the proper spatial development of reproductive floral tissues. Recessive mutations cause extra stamens to form interior to the normal third whorl stamens, at the expense of fourth whorl carpel development. The mutant phenotype is associated with the ectopic expression of the B function genes, AP3 and PI, in the altered floral region, closer to the centre of the flower than in the wild type, and ap3 sup and pi sup double mutants exhibit a phenotype similar to ap3 and pi single mutants. These findings led to SUP being interpreted as an upstream negative regulator of the B function organ-identity genes, acting in the fourth whorl, to establish a boundary between stamen and carpel whorls. Here we show, using molecular cloning and analysis, that it is expressed in the third whorl and acts to maintain this boundary in developing flowers. The putative SUPERMAN protein contains one zinc-finger and a region resembling a basic leucine zipper motif, suggesting a function in transcriptional regulation.

  13. Twin boundaries, interfaces and modulated structures in martensites

    Energy Technology Data Exchange (ETDEWEB)

    Barsch, G.R.

    1990-01-15

    A comprehensive theoretical study with concurrent supporting experimental investigations is being carried out on coherent and semicoherent interfaces in ferroelastic martensites, including twin boundaries and twin bands, heterophase parent/product interfaces and inclusions, and transformation precursors. This work is motivated by the need for a new theoretical basis for investigating the martensite nucleation mechanism and for establishing the conditions for nonclassical nucleation. Soliton-like solutions of a dynamic Ginzburg-Landau continuum theory for ferroelastic martensites are being studied in order to determine the strain distribution, strain energy and dynamical behavior for various geometric configurations as a function of the material parameters, temperature and boundary conditions. Model parameters of the theory consist of the second and higher order elastic constants and the harmonic strain gradient coefficients in the parent phase. X-ray measurements of the transformation strain versus temperature, and ultrasonic velocity and attenuation measurements on biaxially stressed crystals in In{sub 1{minus}x}Tl{sub x} alloys for determining the second and higher order elastic constants in the single domain tetragonal state and for studying the morphology and the dynamic behavior of the martensite interfaces and transformation precursors are in progress.

  14. Nonlinear Vibrations of Multiwalled Carbon Nanotubes under Various Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Hossein Aminikhah

    2011-01-01

    Full Text Available The present work deals with applying the homotopy perturbation method to the problem of the nonlinear oscillations of multiwalled carbon nanotubes embedded in an elastic medium under various boundary conditions. A multiple-beam model is utilized in which the governing equations of each layer are coupled with those of its adjacent ones via the van der Waals interlayer forces. The amplitude-frequency curves for large-amplitude vibrations of single-walled, double-walled, and triple-walled carbon nanotubes are obtained. The influences of some commonly used boundary conditions, changes in material constant of the surrounding elastic medium, and variations of the nanotubes geometrical parameters on the vibration characteristics of multiwalled carbon nanotubes are discussed. The comparison of the generated results with those from the open literature illustrates that the solutions obtained are of very high accuracy and clarifies the capability and the simplicity of the present method. It is worthwhile to say that the results generated are new and can be served as a benchmark for future works.

  15. On relevant boundary perturbations of unitary minimal models

    International Nuclear Information System (INIS)

    Recknagel, A.; Roggenkamp, D.; Schomerus, V.

    2000-01-01

    We consider unitary Virasoro minimal models on the disk with Cardy boundary conditions and discuss deformations by certain relevant boundary operators, analogous to tachyon condensation in string theory. Concentrating on the least relevant boundary field, we can perform a perturbative analysis of renormalization group fixed points. We find that the systems always flow towards stable fixed points which admit no further (non-trivial) relevant perturbations. The new conformal boundary conditions are in general given by superpositions of 'pure' Cardy boundary conditions

  16. Observations of the atmospheric boundary layer height over Abu Dhabi, United Arab Emirates: Investigating boundary layer climatology in arid regions

    Science.gov (United States)

    Marzooqi, Mohamed Al; Basha, Ghouse; Ouarda, Taha B. M. J.; Armstrong, Peter; Molini, Annalisa

    2014-05-01

    Strong sensible heat fluxes and deep turbulent mixing - together with marked dustiness and a low substrate water content - represent a characteristic signature in the boundary layer over hot deserts, resulting in "thicker" mixing layers and peculiar optical properties. Beside these main features however, desert ABLs present extremely complex local structures that have been scarcely addressed in the literature, and whose understanding is essential in modeling processes such as the transport of dust and pollutants, and turbulent fluxes of momentum, heat and water vapor in hyper-arid regions. In this study, we analyze a continuous record of observations of the atmospheric boundary layer (ABL) height from a single lens LiDAR ceilometer operated at Masdar Institute Field Station (24.4oN, 54.6o E, Abu Dhabi, United Arab Emirates), starting March 2013. We compare different methods for the estimation of the ABL height from Ceilometer data such as, classic variance-, gradient-, log gradient- and second derivation-methods as well as recently developed techniques such as the Bayesian Method and Wavelet covariance transform. Our goal is to select the most suited technique for describing the climatology of the ABL in desert environments. Comparison of our results with radiosonde observations collected at the nearby airport of Abu Dhabi indicate that the WCT and the Bayesian method are the most suitable tools to accurately identify the ABL height in all weather conditions. These two methods are used for the definition of diurnal and seasonal climatologies of the boundary layer conditional to different atmospheric stability classes.

  17. County and Parish Boundaries - COUNTY_GOVERNMENT_BOUNDARIES_IDHS_IN: Governmental Boundaries Maintained by County Agencies in Indiana (Indiana Department of Homeland Security, Polygon feature class)

    Data.gov (United States)

    NSGIC State | GIS Inventory — COUNTY_GOVERNMENT_BOUNDARIES_IDHS_IN is a polygon feature class that contains governmental boundaries maintained by county agencies in Indiana, provided by personnel...

  18. Boundary layer height estimation by sodar and sonic anemometer measurements

    International Nuclear Information System (INIS)

    Contini, D; Cava, D; Martano, P; Donateo, A; Grasso, F M

    2008-01-01

    In this paper an analysis of different methods for the calculation of the boundary layer height (BLH) using sodar and ultrasonic anemometer measurements is presented. All the methods used are based on single point surface measurements. In particular the automatic spectral routine developed for Remtech sodar is compared with the results obtained with the parameterization of the vertical velocity variance, with the calculation of a prognostic model and with a parameterization based on horizontal velocity spectra. Results indicate that in unstable conditions the different methods provide similar pattern, with BLH relatively low, even if the parameterization of the vertical velocity variance is affected by a large scatter that limits its efficiency in evaluating the BLH. In stable nocturnal conditions the performances of the Remtech routine are lower with respect to the ones in unstable conditions. The spectral method, applied to sodar or sonic anemometer data, seems to be the most promising in order to develop an efficient routine for BLH determination

  19. Practices at the Boundaries of Business Ethics & Corporate Social Responsibility

    DEFF Research Database (Denmark)

    Weller, Angeli

    In this dissertation, I explore the practices created to manage business ethics and corporate social responsibility in multinational corporations and the relationship between them across three separate but interrelated articles. The first article suggests that these practices are resident...... social responsibility field in the United States, as well as their current articulations of knowledge and competence in their respective fields. The third article is a single case study of a company that purposefully aligned ethics, compliance, corporate social responsibility and sustainability practices....... Practically, this work shows that boundaries exist between business ethics and corporate social responsibility practices, and calls on scholars and managers who seek alignment to both build intentional bridges between these communities and consider alternate trajectories for the evolution of these practices...

  20. Boundary effects on radiative processes of two entangled atoms

    Energy Technology Data Exchange (ETDEWEB)

    Arias, E. [Instituto Politécnico, Universidade do Estado do Rio de Janeiro,28625-570 Nova Friburgo (Brazil); Dueñas, J.G. [Universidade Federal de Minas Gerais,Belo Horizonte, BH 31270-901 (Brazil); Menezes, G. [Grupo de Física Teórica e Matemática Física, Departamento de Física,Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ 23897-000 (Brazil); Svaiter, N.F. [Centro Brasileiro de Pesquisas Físicas,Rio de Janeiro, RJ 22290-180 (Brazil)

    2016-07-29

    We analyze radiative processes of a quantum system composed by two identical two-level atoms interacting with a massless scalar field prepared in the vacuum state in the presence of perfect reflecting flat mirrors. We consider that the atoms are prepared in a stationary maximally entangled state. We investigate the spontaneous transitions rates from the entangled states to the collective ground state induced by vacuum fluctuations. In the empty-space case, the spontaneous decay rates can be enhanced or inhibited depending on the specific entangled state and changes with the distance between the atoms. Next, we consider the presence of perfect mirrors and impose Dirichlet boundary conditions on such surfaces. In the presence of a single mirror the transition rate for the symmetric state undergoes a slight reduction, whereas for the antisymmetric state our results indicate a slightly enhancement. Finally, we investigate the effect of multiple reflections by two perfect mirrors on the transition rates.